Integrate r128344 and r128253 from WebKit

cc/CCSingleThreadProxy.cpp

Index: cc/CCSingleThreadProxy.cpp
diff --git a/cc/CCSingleThreadProxy.cpp b/cc/CCSingleThreadProxy.cpp
index 0a52d64ba10f336e45e03085dc9fc46dd5f0e0ca..763d668935b22f59ac12c8ecf15a7a45ef6720e1 100644
--- a/cc/CCSingleThreadProxy.cpp
+++ b/cc/CCSingleThreadProxy.cpp
@@ -255,6 +255,12 @@ void CCSingleThreadProxy::postAnimationEventsToMainThreadOnImplThread(PassOwnPtr
     m_layerTreeHost->setAnimationEvents(events, wallClockTime);
 }
 
+void CCSingleThreadProxy::releaseContentsTexturesOnImplThread()
+{
+    ASSERT(isImplThread());
+    m_layerTreeHost->reduceContentsTexturesMemoryOnImplThread(0, m_layerTreeHostImpl->resourceProvider());
+}
+
 // Called by the legacy scheduling path (e.g. where render_widget does the scheduling)
 void CCSingleThreadProxy::compositeImmediately()
 {
@@ -280,15 +286,23 @@ bool CCSingleThreadProxy::commitAndComposite()
     if (!m_layerTreeHost->initializeRendererIfNeeded())
         return false;
 
-    if (m_layerTreeHostImpl->contentsTexturesPurged()) {
-        m_layerTreeHost->unlinkAllContentTextures();
+    // Unlink any texture backings that were deleted
+    CCPrioritizedTextureManager::BackingVector evictedContentsTexturesBackings;
+    {
+        DebugScopedSetImplThread implThread;
+        m_layerTreeHost->getEvictedContentTexturesBackings(evictedContentsTexturesBackings);
+    }
+    m_layerTreeHost->unlinkEvictedContentTexturesBackings(evictedContentsTexturesBackings);
+    {
         DebugScopedSetImplThreadAndMainThreadBlocked implAndMainBlocked;
-        m_layerTreeHost->deleteUnlinkedTextures();
+        m_layerTreeHost->deleteEvictedContentTexturesBackings();
     }
 
     CCTextureUpdateQueue queue;
     m_layerTreeHost->updateLayers(queue, m_layerTreeHostImpl->memoryAllocationLimitBytes());
-    m_layerTreeHostImpl->resetContentsTexturesPurged();
+
+    if (m_layerTreeHostImpl->contentsTexturesPurged())
+        m_layerTreeHostImpl->resetContentsTexturesPurged();
 
     m_layerTreeHost->willCommit();
     doCommit(queue);