Fixing 2D canvas invalidation region tracking.

Source/platform/graphics/Canvas2DLayerBridge.cpp

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 440 matching lines @@
     webContext->bindTexture(GL_TEXTURE_2D, 0);
     // Because we are changing the texture binding without going through skia,
     // we must dirty the context.
     m_contextProvider->grContext()->resetContext(kTextureBinding_GrGLBackendState);
 
     // set m_parentLayerBridge to make sure 'this' stays alive as long as it has
     // live mailboxes
     ASSERT(!mailboxInfo->m_parentLayerBridge);
     mailboxInfo->m_parentLayerBridge = this;
     *outMailbox = mailboxInfo->m_mailbox;
+
+    if (m_imageBuffer)
+        m_imageBuffer->didPresent();
+
     return true;
 }
 
 Canvas2DLayerBridge::MailboxInfo* Canvas2DLayerBridge::createMailboxInfo() {
     ASSERT(!m_destructionInProgress);
     MailboxInfo* mailboxInfo;
     for (mailboxInfo = m_mailboxes.begin(); mailboxInfo < m_mailboxes.end(); mailboxInfo++) {
         if (mailboxInfo->m_status == MailboxAvailable) {
             return mailboxInfo;
         }
@@ skipping 73 matching lines @@
 Canvas2DLayerBridge::MailboxInfo::MailboxInfo(const MailboxInfo& other) {
     // This copy constructor should only be used for Vector reallocation
     // Assuming 'other' is to be destroyed, we transfer m_image ownership
     // rather than do a refcount dance.
     memcpy(&m_mailbox, &other.m_mailbox, sizeof(m_mailbox));
     m_image = const_cast<MailboxInfo*>(&other)->m_image.release();
     m_status = other.m_status;
 }
 
 }