Always check weak global references before using them

We hold weak references to Java objects from native code in several
places to avoid circular reference problems. These objects may become
weakly reachable at any time, after which the GC could null our weak
reference, so we have to null-check at every use.

Note that weak references are nulled before the referent is finalized,
so we can't rely on doing work in the finalizer to wait for the
currently executing message to complete and to remove other messages
from the queue.

This effectively reverts
https://android-git.corp.google.com/g/#change,30955

Bug: 4336862
Change-Id: I431fcac11220cb406c26e31aacb9bda7ea22776e

1 files changed, 231 insertions, 89 deletions

diff --git a/Source/WebKit/android/jni/WebViewCore.cpp b/Source/WebKit/android/jni/WebViewCore.cpp
index 494ebea..ded3965 100644
--- a/Source/WebKit/android/jni/WebViewCore.cpp
+++ b/Source/WebKit/android/jni/WebViewCore.cpp
@@ -303,6 +303,13 @@ struct WebViewCore::JavaGlue {
     jmethodID   m_setWebTextViewAutoFillable;
     jmethodID   m_selectAt;
     AutoJObject object(JNIEnv* env) {
+        // We hold a weak reference to the Java WebViewCore to avoid memeory
+        // leaks due to circular references when WebView.destroy() is not
+        // called manually. The WebView and hence the WebViewCore could become
+        // weakly reachable at any time, after which the GC could null our weak
+        // reference, so we have to check the return value of this method at
+        // every use. Note that our weak reference will be nulled before the
+        // WebViewCore is finalized.
         return getRealObject(env, m_obj);
     }
 };
@@ -724,12 +731,13 @@ void WebViewCore::recordPictureSet(PictureSet* content)
     DBG_NAV_LOG("call updateFrameCache");
     updateFrameCache();
     if (m_findIsUp) {
-        LOG_ASSERT(m_javaGlue->m_obj,
-                "A Java widget was not associated with this view bridge!");
+        LOG_ASSERT(m_javaGlue->m_obj, "A Java widget was not associated with this view bridge!");
         JNIEnv* env = JSC::Bindings::getJNIEnv();
-        env->CallVoidMethod(m_javaGlue->object(env).get(),
-                m_javaGlue->m_sendFindAgain);
-        checkException(env);
+        AutoJObject javaObject = m_javaGlue->object(env);
+        if (javaObject.get()) {
+            env->CallVoidMethod(javaObject.get(), m_javaGlue->m_sendFindAgain);
+            checkException(env);
+        }
     }
 }
 
@@ -947,7 +955,10 @@ void WebViewCore::scrollTo(int x, int y, bool animate)
 //    LOGD("WebViewCore::scrollTo(%d %d)\n", x, y);
 
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_scrollTo,
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_scrollTo,
             x, y, animate, false);
     checkException(env);
 }
@@ -956,7 +967,10 @@ void WebViewCore::sendNotifyProgressFinished()
 {
     LOG_ASSERT(m_javaGlue->m_obj, "A Java widget was not associated with this view bridge!");
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_sendNotifyProgressFinished);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_sendNotifyProgressFinished);
     checkException(env);
 }
 
@@ -964,7 +978,10 @@ void WebViewCore::viewInvalidate(const WebCore::IntRect& rect)
 {
     LOG_ASSERT(m_javaGlue->m_obj, "A Java widget was not associated with this view bridge!");
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(),
                         m_javaGlue->m_sendViewInvalidate,
                         rect.x(), rect.y(), rect.maxX(), rect.maxY());
     checkException(env);
@@ -973,14 +990,20 @@ void WebViewCore::viewInvalidate(const WebCore::IntRect& rect)
 void WebViewCore::contentDraw()
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_contentDraw);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_contentDraw);
     checkException(env);
 }
 
 void WebViewCore::layersDraw()
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_layersDraw);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_layersDraw);
     checkException(env);
 }
 
@@ -1027,6 +1050,11 @@ void WebViewCore::didFirstLayout()
     DEBUG_NAV_UI_LOGD("%s", __FUNCTION__);
     LOG_ASSERT(m_javaGlue->m_obj, "A Java widget was not associated with this view bridge!");
 
+    JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+
     const WebCore::KURL& url = m_mainFrame->document()->url();
     if (url.isEmpty())
         return;
@@ -1034,8 +1062,7 @@ void WebViewCore::didFirstLayout()
 
     WebCore::FrameLoadType loadType = m_mainFrame->loader()->loadType();
 
-    JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_didFirstLayout,
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_didFirstLayout,
             loadType == WebCore::FrameLoadTypeStandard
             // When redirect with locked history, we would like to reset the
             // scale factor. This is important for www.yahoo.com as it is
@@ -1055,7 +1082,10 @@ void WebViewCore::updateViewport()
     LOG_ASSERT(m_javaGlue->m_obj, "A Java widget was not associated with this view bridge!");
 
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_updateViewport);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_updateViewport);
     checkException(env);
 }
 
@@ -1065,7 +1095,10 @@ void WebViewCore::restoreScale(float scale, float textWrapScale)
     LOG_ASSERT(m_javaGlue->m_obj, "A Java widget was not associated with this view bridge!");
 
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_restoreScale, scale, textWrapScale);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_restoreScale, scale, textWrapScale);
     checkException(env);
 }
 
@@ -1075,11 +1108,15 @@ void WebViewCore::needTouchEvents(bool need)
     LOG_ASSERT(m_javaGlue->m_obj, "A Java widget was not associated with this view bridge!");
 
 #if ENABLE(TOUCH_EVENTS)
+    JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+
     if (m_forwardingTouchEvents == need)
         return;
 
-    JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_needTouchEvents, need);
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_needTouchEvents, need);
     checkException(env);
 
     m_forwardingTouchEvents = need;
@@ -1093,7 +1130,10 @@ void WebViewCore::requestKeyboardWithSelection(const WebCore::Node* node,
     LOG_ASSERT(m_javaGlue->m_obj, "A Java widget was not associated with this view bridge!");
 
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(),
             m_javaGlue->m_requestKeyboardWithSelection,
             reinterpret_cast<int>(node), selStart, selEnd, m_textGeneration);
     checkException(env);
@@ -1105,8 +1145,10 @@ void WebViewCore::requestKeyboard(bool showKeyboard)
     LOG_ASSERT(m_javaGlue->m_obj, "A Java widget was not associated with this view bridge!");
 
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
-            m_javaGlue->m_requestKeyboard, showKeyboard);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_requestKeyboard, showKeyboard);
     checkException(env);
 }
 
@@ -2738,8 +2780,10 @@ String WebViewCore::formatMarkup(DOMSelection* selection)
 void WebViewCore::selectAt(int x, int y)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_selectAt,
-        x, y);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_selectAt, x, y);
     checkException(env);
 }
 
@@ -2888,19 +2932,24 @@ static jobjectArray makeLabelArray(JNIEnv* env, const uint16_t** labels, size_t
     return array;
 }
 
-void WebViewCore::openFileChooser(PassRefPtr<WebCore::FileChooser> chooser) {
+void WebViewCore::openFileChooser(PassRefPtr<WebCore::FileChooser> chooser)
+{
+    JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+
     if (!chooser)
         return;
-    JNIEnv* env = JSC::Bindings::getJNIEnv();
 
     WTF::String acceptType = chooser->acceptTypes();
     jstring jAcceptType = wtfStringToJstring(env, acceptType, true);
     jstring jName = (jstring) env->CallObjectMethod(
-            m_javaGlue->object(env).get(), m_javaGlue->m_openFileChooser, jAcceptType);
+            javaObject.get(), m_javaGlue->m_openFileChooser, jAcceptType);
     checkException(env);
     env->DeleteLocalRef(jAcceptType);
 
-    const UChar* string = static_cast<const UChar*>(env->GetStringChars(jName, NULL));
+    const UChar* string = static_cast<const UChar*>(env->GetStringChars(jName, 0));
 
     if (!string)
         return;
@@ -2915,14 +2964,18 @@ void WebViewCore::openFileChooser(PassRefPtr<WebCore::FileChooser> chooser) {
 void WebViewCore::listBoxRequest(WebCoreReply* reply, const uint16_t** labels, size_t count, const int enabled[], size_t enabledCount,
         bool multiple, const int selected[], size_t selectedCountOrSelection)
 {
+    LOG_ASSERT(m_javaGlue->m_obj, "No java widget associated with this view!");
+
+    JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+
     // If m_popupReply is not null, then we already have a list showing.
     if (m_popupReply != 0)
         return;
 
-    LOG_ASSERT(m_javaGlue->m_obj, "No java widget associated with this view!");
-
     // Create an array of java Strings for the drop down.
-    JNIEnv* env = JSC::Bindings::getJNIEnv();
     jobjectArray labelArray = makeLabelArray(env, labels, count);
 
     // Create an array determining whether each item is enabled.
@@ -2947,13 +3000,13 @@ void WebViewCore::listBoxRequest(WebCoreReply* reply, const uint16_t** labels, s
         }
         env->ReleaseIntArrayElements(selectedArray, selArray, 0);
 
-        env->CallVoidMethod(m_javaGlue->object(env).get(),
+        env->CallVoidMethod(javaObject.get(),
                 m_javaGlue->m_requestListBox, labelArray, enabledArray,
                 selectedArray);
         env->DeleteLocalRef(selectedArray);
     } else {
         // Pass up the single selection.
-        env->CallVoidMethod(m_javaGlue->object(env).get(),
+        env->CallVoidMethod(javaObject.get(),
                 m_javaGlue->m_requestSingleListBox, labelArray, enabledArray,
                 selectedCountOrSelection);
     }
@@ -3267,8 +3320,10 @@ void WebViewCore::focusNodeChanged(const WebCore::Node* newFocus)
         m_shouldPaintCaret = true;
     else if (m_blurringNodePointer) {
         JNIEnv* env = JSC::Bindings::getJNIEnv();
-        env->CallVoidMethod(m_javaGlue->object(env).get(),
-                m_javaGlue->m_formDidBlur, m_blurringNodePointer);
+        AutoJObject javaObject = m_javaGlue->object(env);
+        if (!javaObject.get())
+            return;
+        env->CallVoidMethod(javaObject.get(), m_javaGlue->m_formDidBlur, m_blurringNodePointer);
         checkException(env);
         m_blurringNodePointer = 0;
     }
@@ -3276,9 +3331,12 @@ void WebViewCore::focusNodeChanged(const WebCore::Node* newFocus)
 
 void WebViewCore::addMessageToConsole(const WTF::String& message, unsigned int lineNumber, const WTF::String& sourceID, int msgLevel) {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
     jstring jMessageStr = wtfStringToJstring(env, message);
     jstring jSourceIDStr = wtfStringToJstring(env, sourceID);
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
+    env->CallVoidMethod(javaObject.get(),
             m_javaGlue->m_addMessageToConsole, jMessageStr, lineNumber,
             jSourceIDStr, msgLevel);
     env->DeleteLocalRef(jMessageStr);
@@ -3289,52 +3347,68 @@ void WebViewCore::addMessageToConsole(const WTF::String& message, unsigned int l
 void WebViewCore::jsAlert(const WTF::String& url, const WTF::String& text)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
     jstring jInputStr = wtfStringToJstring(env, text);
     jstring jUrlStr = wtfStringToJstring(env, url);
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_jsAlert, jUrlStr, jInputStr);
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_jsAlert, jUrlStr, jInputStr);
     env->DeleteLocalRef(jInputStr);
     env->DeleteLocalRef(jUrlStr);
     checkException(env);
 }
 
-void WebViewCore::exceededDatabaseQuota(const WTF::String& url, const WTF::String& databaseIdentifier, const unsigned long long currentQuota, unsigned long long estimatedSize)
+bool WebViewCore::exceededDatabaseQuota(const WTF::String& url, const WTF::String& databaseIdentifier, const unsigned long long currentQuota, unsigned long long estimatedSize)
 {
 #if ENABLE(DATABASE)
     JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return false;
     jstring jDatabaseIdentifierStr = wtfStringToJstring(env, databaseIdentifier);
     jstring jUrlStr = wtfStringToJstring(env, url);
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
+    env->CallVoidMethod(javaObject.get(),
             m_javaGlue->m_exceededDatabaseQuota, jUrlStr,
             jDatabaseIdentifierStr, currentQuota, estimatedSize);
     env->DeleteLocalRef(jDatabaseIdentifierStr);
     env->DeleteLocalRef(jUrlStr);
     checkException(env);
+    return true;
 #endif
 }
 
-void WebViewCore::reachedMaxAppCacheSize(const unsigned long long spaceNeeded)
+bool WebViewCore::reachedMaxAppCacheSize(const unsigned long long spaceNeeded)
 {
 #if ENABLE(OFFLINE_WEB_APPLICATIONS)
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
-            m_javaGlue->m_reachedMaxAppCacheSize, spaceNeeded);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return false;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_reachedMaxAppCacheSize, spaceNeeded);
     checkException(env);
+    return true;
 #endif
 }
 
 void WebViewCore::populateVisitedLinks(WebCore::PageGroup* group)
 {
-    m_groupForVisitedLinks = group;
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_populateVisitedLinks);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    m_groupForVisitedLinks = group;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_populateVisitedLinks);
     checkException(env);
 }
 
 void WebViewCore::geolocationPermissionsShowPrompt(const WTF::String& origin)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
     jstring originString = wtfStringToJstring(env, origin);
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
+    env->CallVoidMethod(javaObject.get(),
                         m_javaGlue->m_geolocationPermissionsShowPrompt,
                         originString);
     env->DeleteLocalRef(originString);
@@ -3344,16 +3418,20 @@ void WebViewCore::geolocationPermissionsShowPrompt(const WTF::String& origin)
 void WebViewCore::geolocationPermissionsHidePrompt()
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
-                        m_javaGlue->m_geolocationPermissionsHidePrompt);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_geolocationPermissionsHidePrompt);
     checkException(env);
 }
 
 jobject WebViewCore::getDeviceMotionService()
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    jobject object = env->CallObjectMethod(m_javaGlue->object(env).get(),
-                                           m_javaGlue->m_getDeviceMotionService);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return 0;
+    jobject object = env->CallObjectMethod(javaObject.get(), m_javaGlue->m_getDeviceMotionService);
     checkException(env);
     return object;
 }
@@ -3361,8 +3439,10 @@ jobject WebViewCore::getDeviceMotionService()
 jobject WebViewCore::getDeviceOrientationService()
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    jobject object = env->CallObjectMethod(m_javaGlue->object(env).get(),
-                                           m_javaGlue->m_getDeviceOrientationService);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return 0;
+    jobject object = env->CallObjectMethod(javaObject.get(), m_javaGlue->m_getDeviceOrientationService);
     checkException(env);
     return object;
 }
@@ -3370,9 +3450,12 @@ jobject WebViewCore::getDeviceOrientationService()
 bool WebViewCore::jsConfirm(const WTF::String& url, const WTF::String& text)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return false;
     jstring jInputStr = wtfStringToJstring(env, text);
     jstring jUrlStr = wtfStringToJstring(env, url);
-    jboolean result = env->CallBooleanMethod(m_javaGlue->object(env).get(), m_javaGlue->m_jsConfirm, jUrlStr, jInputStr);
+    jboolean result = env->CallBooleanMethod(javaObject.get(), m_javaGlue->m_jsConfirm, jUrlStr, jInputStr);
     env->DeleteLocalRef(jInputStr);
     env->DeleteLocalRef(jUrlStr);
     checkException(env);
@@ -3382,10 +3465,13 @@ bool WebViewCore::jsConfirm(const WTF::String& url, const WTF::String& text)
 bool WebViewCore::jsPrompt(const WTF::String& url, const WTF::String& text, const WTF::String& defaultValue, WTF::String& result)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return false;
     jstring jUrlStr = wtfStringToJstring(env, url);
     jstring jInputStr = wtfStringToJstring(env, text);
     jstring jDefaultStr = wtfStringToJstring(env, defaultValue);
-    jstring returnVal = static_cast<jstring>(env->CallObjectMethod(m_javaGlue->object(env).get(), m_javaGlue->m_jsPrompt, jUrlStr, jInputStr, jDefaultStr));
+    jstring returnVal = static_cast<jstring>(env->CallObjectMethod(javaObject.get(), m_javaGlue->m_jsPrompt, jUrlStr, jInputStr, jDefaultStr));
     env->DeleteLocalRef(jUrlStr);
     env->DeleteLocalRef(jInputStr);
     env->DeleteLocalRef(jDefaultStr);
@@ -3403,9 +3489,12 @@ bool WebViewCore::jsPrompt(const WTF::String& url, const WTF::String& text, cons
 bool WebViewCore::jsUnload(const WTF::String& url, const WTF::String& message)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return false;
     jstring jInputStr = wtfStringToJstring(env, message);
     jstring jUrlStr = wtfStringToJstring(env, url);
-    jboolean result = env->CallBooleanMethod(m_javaGlue->object(env).get(), m_javaGlue->m_jsUnload, jUrlStr, jInputStr);
+    jboolean result = env->CallBooleanMethod(javaObject.get(), m_javaGlue->m_jsUnload, jUrlStr, jInputStr);
     env->DeleteLocalRef(jInputStr);
     env->DeleteLocalRef(jUrlStr);
     checkException(env);
@@ -3415,7 +3504,10 @@ bool WebViewCore::jsUnload(const WTF::String& url, const WTF::String& message)
 bool WebViewCore::jsInterrupt()
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    jboolean result = env->CallBooleanMethod(m_javaGlue->object(env).get(), m_javaGlue->m_jsInterrupt);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return false;
+    jboolean result = env->CallBooleanMethod(javaObject.get(), m_javaGlue->m_jsInterrupt);
     checkException(env);
     return result;
 }
@@ -3430,10 +3522,18 @@ jobject
 WebViewCore::getWebViewJavaObject()
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    return env->GetObjectField(m_javaGlue->object(env).get(), gWebViewCoreFields.m_webView);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return 0;
+    return env->GetObjectField(javaObject.get(), gWebViewCoreFields.m_webView);
 }
 
-void WebViewCore::updateTextSelection() {
+void WebViewCore::updateTextSelection()
+{
+    JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
     WebCore::Node* focusNode = currentFocus();
     if (!focusNode)
         return;
@@ -3441,8 +3541,7 @@ void WebViewCore::updateTextSelection() {
     if (!renderer || (!renderer->isTextArea() && !renderer->isTextField()))
         return;
     RenderTextControl* rtc = static_cast<RenderTextControl*>(renderer);
-    JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
+    env->CallVoidMethod(javaObject.get(),
             m_javaGlue->m_updateTextSelection, reinterpret_cast<int>(focusNode),
             rtc->selectionStart(), rtc->selectionEnd(), m_textGeneration);
     checkException(env);
@@ -3451,17 +3550,20 @@ void WebViewCore::updateTextSelection() {
 void WebViewCore::updateTextfield(WebCore::Node* ptr, bool changeToPassword,
         const WTF::String& text)
 {
+    JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
     if (m_blockTextfieldUpdates)
         return;
-    JNIEnv* env = JSC::Bindings::getJNIEnv();
     if (changeToPassword) {
-        env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_updateTextfield,
+        env->CallVoidMethod(javaObject.get(), m_javaGlue->m_updateTextfield,
                 (int) ptr, true, 0, m_textGeneration);
         checkException(env);
         return;
     }
     jstring string = wtfStringToJstring(env, text);
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_updateTextfield,
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_updateTextfield,
             (int) ptr, false, string, m_textGeneration);
     env->DeleteLocalRef(string);
     checkException(env);
@@ -3470,8 +3572,10 @@ void WebViewCore::updateTextfield(WebCore::Node* ptr, bool changeToPassword,
 void WebViewCore::clearTextEntry()
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
-        m_javaGlue->m_clearTextEntry);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_clearTextEntry);
 }
 
 void WebViewCore::setBackgroundColor(SkColor c)
@@ -3493,10 +3597,13 @@ void WebViewCore::setBackgroundColor(SkColor c)
 jclass WebViewCore::getPluginClass(const WTF::String& libName, const char* className)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return 0;
 
     jstring libString = wtfStringToJstring(env, libName);
     jstring classString = env->NewStringUTF(className);
-    jobject pluginClass = env->CallObjectMethod(m_javaGlue->object(env).get(),
+    jobject pluginClass = env->CallObjectMethod(javaObject.get(),
                                            m_javaGlue->m_getPluginClass,
                                            libString, classString);
     checkException(env);
@@ -3505,36 +3612,41 @@ jclass WebViewCore::getPluginClass(const WTF::String& libName, const char* class
     env->DeleteLocalRef(libString);
     env->DeleteLocalRef(classString);
 
-    if (pluginClass != NULL) {
+    if (pluginClass != 0) {
         return static_cast<jclass>(pluginClass);
     } else {
-        return NULL;
+        return 0;
     }
 }
 
 void WebViewCore::showFullScreenPlugin(jobject childView, NPP npp)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    AutoJObject obj = m_javaGlue->object(env);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
 
-    env->CallVoidMethod(obj.get(),
-                        m_javaGlue->m_showFullScreenPlugin, childView, (int)npp);
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_showFullScreenPlugin, childView, reinterpret_cast<int>(npp));
     checkException(env);
 }
 
 void WebViewCore::hideFullScreenPlugin()
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
-                        m_javaGlue->m_hideFullScreenPlugin);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_hideFullScreenPlugin);
     checkException(env);
 }
 
 jobject WebViewCore::createSurface(jobject view)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    jobject result = env->CallObjectMethod(m_javaGlue->object(env).get(),
-                                           m_javaGlue->m_createSurface, view);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return 0;
+    jobject result = env->CallObjectMethod(javaObject.get(), m_javaGlue->m_createSurface, view);
     checkException(env);
     return result;
 }
@@ -3542,7 +3654,10 @@ jobject WebViewCore::createSurface(jobject view)
 jobject WebViewCore::addSurface(jobject view, int x, int y, int width, int height)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    jobject result = env->CallObjectMethod(m_javaGlue->object(env).get(),
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return 0;
+    jobject result = env->CallObjectMethod(javaObject.get(),
                                            m_javaGlue->m_addSurface,
                                            view, x, y, width, height);
     checkException(env);
@@ -3552,7 +3667,10 @@ jobject WebViewCore::addSurface(jobject view, int x, int y, int width, int heigh
 void WebViewCore::updateSurface(jobject childView, int x, int y, int width, int height)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(),
                         m_javaGlue->m_updateSurface, childView,
                         x, y, width, height);
     checkException(env);
@@ -3561,16 +3679,21 @@ void WebViewCore::updateSurface(jobject childView, int x, int y, int width, int
 void WebViewCore::destroySurface(jobject childView)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_destroySurface, childView);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_destroySurface, childView);
     checkException(env);
 }
 
 jobject WebViewCore::getContext()
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    AutoJObject obj = m_javaGlue->object(env);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return 0;
 
-    jobject result = env->CallObjectMethod(obj.get(), m_javaGlue->m_getContext);
+    jobject result = env->CallObjectMethod(javaObject.get(), m_javaGlue->m_getContext);
     checkException(env);
     return result;
 }
@@ -3578,7 +3701,10 @@ jobject WebViewCore::getContext()
 void WebViewCore::keepScreenOn(bool screenOn) {
     if ((screenOn && m_screenOnCounter == 0) || (!screenOn && m_screenOnCounter == 1)) {
         JNIEnv* env = JSC::Bindings::getJNIEnv();
-        env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_keepScreenOn, screenOn);
+        AutoJObject javaObject = m_javaGlue->object(env);
+        if (!javaObject.get())
+            return;
+        env->CallVoidMethod(javaObject.get(), m_javaGlue->m_keepScreenOn, screenOn);
         checkException(env);
     }
 
@@ -3609,7 +3735,10 @@ void WebViewCore::showRect(int left, int top, int width, int height,
         float xPercentInView, float yPercentInDoc, float yPercentInView)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_showRect,
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_showRect,
             left, top, width, height, contentWidth, contentHeight,
             xPercentInDoc, xPercentInView, yPercentInDoc, yPercentInView);
     checkException(env);
@@ -3618,24 +3747,30 @@ void WebViewCore::showRect(int left, int top, int width, int height,
 void WebViewCore::centerFitRect(int x, int y, int width, int height)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
-            m_javaGlue->m_centerFitRect, x, y, width, height);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_centerFitRect, x, y, width, height);
     checkException(env);
 }
 
-
 void WebViewCore::setScrollbarModes(ScrollbarMode horizontalMode, ScrollbarMode verticalMode)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_setScrollbarModes,
-            horizontalMode, verticalMode);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_setScrollbarModes, horizontalMode, verticalMode);
     checkException(env);
 }
 
 void WebViewCore::notifyWebAppCanBeInstalled()
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_setInstallableWebApp);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_setInstallableWebApp);
     checkException(env);
 }
 
@@ -3643,9 +3778,11 @@ void WebViewCore::notifyWebAppCanBeInstalled()
 void WebViewCore::enterFullscreenForVideoLayer(int layerId, const WTF::String& url)
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
     jstring jUrlStr = wtfStringToJstring(env, url);
-    env->CallVoidMethod(m_javaGlue->object(env).get(),
-                        m_javaGlue->m_enterFullscreenForVideoLayer, layerId, jUrlStr);
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_enterFullscreenForVideoLayer, layerId, jUrlStr);
     checkException(env);
 }
 #endif
@@ -3654,8 +3791,11 @@ void WebViewCore::setWebTextViewAutoFillable(int queryId, const string16& previe
 {
 #if ENABLE(WEB_AUTOFILL)
     JNIEnv* env = JSC::Bindings::getJNIEnv();
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return;
     jstring preview = env->NewString(previewSummary.data(), previewSummary.length());
-    env->CallVoidMethod(m_javaGlue->object(env).get(), m_javaGlue->m_setWebTextViewAutoFillable, queryId, preview);
+    env->CallVoidMethod(javaObject.get(), m_javaGlue->m_setWebTextViewAutoFillable, queryId, preview);
     env->DeleteLocalRef(preview);
 #endif
 }
@@ -3663,8 +3803,10 @@ void WebViewCore::setWebTextViewAutoFillable(int queryId, const string16& previe
 bool WebViewCore::drawIsPaused() const
 {
     JNIEnv* env = JSC::Bindings::getJNIEnv();
-    return env->GetBooleanField(m_javaGlue->object(env).get(),
-        gWebViewCoreFields.m_drawIsPaused);
+    AutoJObject javaObject = m_javaGlue->object(env);
+    if (!javaObject.get())
+        return false;
+    return env->GetBooleanField(javaObject.get(), gWebViewCoreFields.m_drawIsPaused);
 }
 
 #if USE(CHROME_NETWORK_STACK)