2 files changed, 28 insertions, 16 deletions

diff --git a/Source/WebCore/platform/graphics/android/BaseTile.cpp b/Source/WebCore/platform/graphics/android/BaseTile.cpp
index dc17a21..a4ce788 100644
--- a/Source/WebCore/platform/graphics/android/BaseTile.cpp
+++ b/Source/WebCore/platform/graphics/android/BaseTile.cpp
@@ -135,13 +135,12 @@ void BaseTile::reserveTexture()
     if (texture && m_backTexture != texture) {
         m_swapDrawCount = 0; // no longer ready to swap
         m_backTexture = texture;
-
-        // this is to catch when the front texture is stolen from beneath us. We
-        // should refine the stealing method to be simpler, and not require last
-        // moment checks like this
-        if (!m_frontTexture)
-            m_dirty = true;
     }
+
+    // a texture reservation will only happen if we're dirty, or ready to
+    // swap. if it's the former, ensure it's marked dirty.
+    if (!m_swapDrawCount)
+        m_dirty = true;
 }
 
 bool BaseTile::removeTexture(BaseTileTexture* texture)
@@ -150,12 +149,15 @@ bool BaseTile::removeTexture(BaseTileTexture* texture)
          this, m_backTexture, m_frontTexture, m_page);
     // We update atomically, so paintBitmap() can see the correct value
     android::AutoMutex lock(m_atomicSync);
-    if (m_frontTexture == texture) {
+    if (m_frontTexture == texture)
         m_frontTexture = 0;
-        m_dirty = true;
-    }
     if (m_backTexture == texture)
         m_backTexture = 0;
+
+    // mark dirty regardless of which texture was taken - the back texture may
+    // have been ready to swap
+    m_dirty = true;
+
     return true;
 }
 
diff --git a/Source/WebCore/platform/graphics/android/TilesManager.cpp b/Source/WebCore/platform/graphics/android/TilesManager.cpp
index ee35ce2..e1d7665 100644
--- a/Source/WebCore/platform/graphics/android/TilesManager.cpp
+++ b/Source/WebCore/platform/graphics/android/TilesManager.cpp
@@ -267,11 +267,13 @@ BaseTileTexture* TilesManager::getAvailableTexture(BaseTile* owner)
     }
 
     // The heuristic for selecting a texture is as follows:
-    //  1. If a tile isn't owned, break with that one
-    //  2. Don't let tiles acquire their front textures
-    //  3. If we find a tile in the same page with a different scale,
+    //  1. Skip textures currently being painted, they can't be painted while
+    //         busy anyway
+    //  2. If a tile isn't owned, break with that one
+    //  3. Don't let tiles acquire their front textures
+    //  4. If we find a tile in the same page with a different scale,
     //         it's old and not visible. Break with that one
-    //  4. Otherwise, use the least recently prepared tile, but ignoring tiles
+    //  5. Otherwise, use the least recently prepared tile, but ignoring tiles
     //         drawn in the last frame to avoid flickering
 
     BaseTileTexture* farthestTexture = 0;
@@ -280,15 +282,23 @@ BaseTileTexture* TilesManager::getAvailableTexture(BaseTile* owner)
     for (unsigned int i = 0; i < max; i++) {
         BaseTileTexture* texture = (*availableTexturePool)[i];
         TextureOwner* currentOwner = texture->owner();
+
+        if (texture->busy()) {
+            // don't bother, since the acquire() will likely fail
+            continue;
+        }
+
         if (!currentOwner) {
+            // unused texture! take it!
             farthestTexture = texture;
             break;
         }
 
-        // Don't let a tile acquire its own front texture, as the acquisition
-        // logic doesn't handle that
-        if (currentOwner == owner)
+        if (currentOwner == owner) {
+            // Don't let a tile acquire its own front texture, as the
+            // acquisition logic doesn't handle that
             continue;
+        }
 
         if (currentOwner->page() == owner->page() && texture->scale() != owner->scale()) {
             // if we render the back page with one scale, then another while