Expose GpuMemoryBufferId through glGetImageivCHROMIUM.

third_party/WebKit/Source/platform/graphics/gpu/DrawingBufferTest.cpp

 /*
  * Copyright (C) 2013 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 88 matching lines @@
     {
         return GL_FRAMEBUFFER_COMPLETE;
     }
 
     void GetIntegerv(GLenum pname, GLint* value) override
     {
         if (pname == GL_MAX_TEXTURE_SIZE)
             *value = 1024;
     }
 
+    void GetImageivCHROMIUM(GLuint imageId, GLenum pname, GLint* data) override
+    {
+        if (pname == GC3D_GPU_MEMORY_BUFFER_ID)
+            *data = 1;
+        else
+            *data = -1;
+    }
+
     void GenMailboxCHROMIUM(GLbyte* mailbox) override
     {
         ++m_currentMailboxByte;
         WebExternalTextureMailbox temp;
         memset(mailbox, m_currentMailboxByte, sizeof(temp.name));
     }
 
     void ProduceTextureDirectCHROMIUM(GLuint texture, GLenum target, const GLbyte* mailbox) override
     {
         ASSERT_EQ(target, drawingBufferTextureTarget(m_allowImageChromium));
@@ skipping 640 matching lines @@
     m_drawingBuffer->markContentsChanged();
     EXPECT_TRUE(m_drawingBuffer->prepareMailbox(&mailbox, 0));
     EXPECT_EQ(initialSize, m_gl->mostRecentlyProducedSize());
     EXPECT_FALSE(mailbox.allowOverlay);
 
     m_drawingBuffer->mailboxReleased(mailbox, false);
     m_drawingBuffer->beginDestruction();
 }
 
 } // namespace blink