Check return values for null.

When a Display has been removed there is a delay until all of its
windows have been removed. Therefore there is a possibility that
WindowState.getDisplayContent() returns null. Guard against that
possibility.

Fixes bug 13616765.

Change-Id: Ia2074d293b0e1bd4ca2cd14aeb4a2cc09ed9f41e

2 files changed, 22 insertions, 4 deletions

diff --git a/services/core/java/com/android/server/wm/WindowManagerService.java b/services/core/java/com/android/server/wm/WindowManagerService.java
index 3b11c4e..332097b 100644
--- a/services/core/java/com/android/server/wm/WindowManagerService.java
+++ b/services/core/java/com/android/server/wm/WindowManagerService.java
@@ -917,6 +917,10 @@ public class WindowManagerService extends IWindowManager.Stub
         final IWindow client = win.mClient;
         final WindowToken token = win.mToken;
         final DisplayContent displayContent = win.getDisplayContent();
+        if (displayContent == null) {
+            // It doesn't matter this display is going away.
+            return 0;
+        }
 
         final WindowList windows = win.getWindowList();
         final int N = windows.size();
@@ -1094,6 +1098,9 @@ public class WindowManagerService extends IWindowManager.Stub
     private void addAttachedWindowToListLocked(final WindowState win, boolean addToToken) {
         final WindowToken token = win.mToken;
         final DisplayContent displayContent = win.getDisplayContent();
+        if (displayContent == null) {
+            return;
+        }
         final WindowState attached = win.mAttachedWindow;
 
         WindowList tokenWindowList = getTokenWindowsOnDisplay(token, displayContent);
@@ -2251,6 +2258,11 @@ public class WindowManagerService extends IWindowManager.Stub
                 return WindowManagerGlobal.ADD_APP_EXITING;
             }
 
+            if (win.getDisplayContent() == null) {
+                Slog.w(TAG, "Adding window to Display that has been removed.");
+                return WindowManagerGlobal.ADD_INVALID_DISPLAY;
+            }
+
             mPolicy.adjustWindowParamsLw(win.mAttrs);
             win.setShowToOwnerOnlyLocked(mPolicy.checkShowToOwnerOnly(attrs));
 
@@ -2744,7 +2756,7 @@ public class WindowManagerService extends IWindowManager.Stub
             return;
         }
 
-        final DisplayInfo displayInfo = window.getDisplayContent().getDisplayInfo();
+        final DisplayInfo displayInfo = displayContent.getDisplayInfo();
         final RectF dispRect = new RectF(0, 0,
                 displayInfo.logicalWidth, displayInfo.logicalHeight);
         matrix.mapRect(dispRect);
diff --git a/services/core/java/com/android/server/wm/WindowStateAnimator.java b/services/core/java/com/android/server/wm/WindowStateAnimator.java
index 93f6d22..1ff0afb 100644
--- a/services/core/java/com/android/server/wm/WindowStateAnimator.java
+++ b/services/core/java/com/android/server/wm/WindowStateAnimator.java
@@ -171,9 +171,15 @@ class WindowStateAnimator {
         mAnimator = service.mAnimator;
         mPolicy = service.mPolicy;
         mContext = service.mContext;
-        final DisplayInfo displayInfo = win.getDisplayContent().getDisplayInfo();
-        mAnimDw = displayInfo.appWidth;
-        mAnimDh = displayInfo.appHeight;
+        final DisplayContent displayContent = win.getDisplayContent();
+        if (displayContent != null) {
+            final DisplayInfo displayInfo = displayContent.getDisplayInfo();
+            mAnimDw = displayInfo.appWidth;
+            mAnimDh = displayInfo.appHeight;
+        } else {
+            Slog.w(TAG, "WindowStateAnimator ctor: Display has been removed");
+            // This is checked on return and dealt with.
+        }
 
         mWin = win;
         mAttachedWinAnimator = win.mAttachedWindow == null