Remove usage of kReturnToCache_FlagBit in C2D layer bridge.

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 301 matching lines @@
     if (!mailboxInfo)
         return;
 
     ASSERT(mailboxInfo->m_status == MailboxReleased);
     if (mailboxInfo->m_mailbox.syncPoint) {
         context()->waitSyncPoint(mailboxInfo->m_mailbox.syncPoint);
         mailboxInfo->m_mailbox.syncPoint = 0;
     }
     // Invalidate texture state in case the compositor altered it since the copy-on-write.
     if (mailboxInfo->m_image) {
-        if (isHidden() || releasedMailboxHasExpired())
-            mailboxInfo->m_image->getTexture()->resetFlag(static_cast<GrTextureFlags>(GrTexture::kReturnToCache_FlagBit));
         mailboxInfo->m_image->getTexture()->textureParamsModified();
         mailboxInfo->m_image.clear();
     }
     mailboxInfo->m_status = MailboxAvailable;
     m_releasedMailboxInfoIndex = InvalidMailboxIndex;
     Canvas2DLayerManager::get().layerTransientResourceAllocationChanged(this);
 }
 
 WebGraphicsContext3D* Canvas2DLayerBridge::context()
 {
@@ skipping 260 matching lines @@
     // This copy constructor should only be used for Vector reallocation
     // Assuming 'other' is to be destroyed, we transfer m_image and
     // m_parentLayerBridge 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_parentLayerBridge = const_cast<MailboxInfo*>(&other)->m_parentLayerBridge.release();
     m_status = other.m_status;
 }
 
 } // namespace blink