Expose GpuMemoryBufferId through glGetImageivCHROMIUM.

third_party/WebKit/Source/platform/graphics/gpu/DrawingBuffer.h

 /*
  * Copyright (c) 2010, 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 232 matching lines @@
         GLenum creationInternalColorFormat = 0;
         GLenum colorFormat = 0;
     };
 
     // If we used CHROMIUM_image as the backing storage for our buffers,
     // we need to know the mapping from texture id to image.
     struct TextureInfo {
         DISALLOW_NEW();
         GLuint textureId = 0;
         GLuint imageId = 0;
+
+        // A GpuMemoryBuffer is a concept that the compositor understands. and
+        // is able to operate on. The id is scoped to renderer process.
+        GLint gpuMemoryBufferId = -1;
+
         TextureParameters parameters;
     };
 
     struct MailboxInfo : public RefCounted<MailboxInfo> {
         WTF_MAKE_NONCOPYABLE(MailboxInfo);
 
     public:
         MailboxInfo() {}
 
         WebExternalTextureMailbox mailbox;
@@ skipping 177 matching lines @@
     // used to resize the Canvas.
     SkBitmap m_resizingBitmap;
 
     // Used to flip a bitmap vertically.
     Vector<uint8_t> m_scanline;
 };
 
 } // namespace blink
 
 #endif // DrawingBuffer_h