WIP: Adjust externally allocated memory when ImageBitmap is transferred

third_party/WebKit/Source/platform/graphics/StaticBitmapImage.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef StaticBitmapImage_h
 #define StaticBitmapImage_h
 
 #include "gpu/command_buffer/common/mailbox.h"
 #include "gpu/command_buffer/common/sync_token.h"
 #include "platform/graphics/Image.h"
@@ skipping 21 matching lines @@
 
   // Methods have common implementation for all sub-classes
   bool currentFrameIsComplete() override { return true; }
   void destroyDecodedData() {}
 
   // Methods that have a default implementation, and overrided by only one
   // sub-class
   virtual bool hasMailbox() { return false; }
 
   virtual void transfer() {}
+  virtual void registerExternalAllocationWithCurrentContext() {}
+  virtual void unregisterExternalAllocationWithCurrentContext() {}

[Justin Novosad, 2017/04/04 16:15:15]

Would be better to register/unregister right here in StaticBitmapImage instead
of delegating to subclass via virtual.  Rationale: AcceleratedStaticBitmapImage
should also trigger GCs,  even though it does not technically consume RAM, GPU
memory is still a precious resource that needs to be freed.

 
   // Methods overrided by AcceleratedStaticBitmapImage only
   virtual void copyToTexture(WebGraphicsContext3DProvider*,
                              GLuint,
                              GLenum,
                              GLenum,
                              bool) {
     NOTREACHED();
   }
   virtual void ensureMailbox() { NOTREACHED(); }
@@ skipping 26 matching lines @@
   // info. They applied to both UnacceleratedStaticBitmapImage and
   // AcceleratedStaticBitmapImage. To change these two properties, the call
   // site would have to call the API setOriginClean() and setPremultiplied().
   bool m_isOriginClean = true;
   bool m_isPremultiplied = true;
 };
 
 }  // namespace blink
 
 #endif