Let canvas decide how to handle the case of resource lost reported by client: 2D part

public/platform/WebExternalTextureLayerClient.h

 /*
  * 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 25 matching lines @@
 struct WebExternalTextureMailbox;
 
 class BLINK_PLATFORM_EXPORT WebExternalTextureLayerClient {
 public:
     // Returns true and provides a mailbox if a new frame is available. If the WebExternalBitmap
     // isn't 0, then it should also be filled in with the contents of this frame.
     // Returns false if no new data is available and the old mailbox and bitmap are to be reused.
     virtual bool prepareMailbox(WebExternalTextureMailbox*, WebExternalBitmap* = 0) = 0;
 
     // Notifies the client when a mailbox is no longer in use by the compositor and provides
-    // a sync point to wait on before the mailbox could be consumes again by the client.
-    virtual void mailboxReleased(const WebExternalTextureMailbox&) = 0;
+    // a sync point to wait on before the mailbox could be consumes again by the client. The
+    // boolean flag indicates if the mailbox resource is treated as lost by client.
+    // FIXME(hmin): Remove the default value for lostResource once the chromium part CL at
+    // https://codereview.chromium.org/369823002 is landed.
+    virtual void mailboxReleased(const WebExternalTextureMailbox&, bool lostResource = false) = 0;
 
 protected:
     virtual ~WebExternalTextureLayerClient() { }
 };
 
 } // namespace blink
 
 #endif // WebExternalTextureLayerClient_h