Perform glReadPixels with PBOs in the gpu, if PBOs are available.

webkit/common/gpu/webgraphicscontext3d_in_process_command_buffer_impl.h

 // Copyright (c) 2012 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 WEBKIT_COMMON_GPU_WEBGRAPHICSCONTEXT3D_IN_PROCESS_COMMAND_BUFFER_IMPL_H_
 #define WEBKIT_COMMON_GPU_WEBGRAPHICSCONTEXT3D_IN_PROCESS_COMMAND_BUFFER_IMPL_H_
 
 #if defined(ENABLE_GPU)
 
 #include <vector>
@@ skipping 526 matching lines @@
       WGC3Denum format,
       WGC3Denum type,
       const void* pixels);
   virtual void waitAsyncTexImage2DCHROMIUM(WGC3Denum target);
 
   virtual void drawBuffersEXT(WGC3Dsizei n, const WGC3Denum* bufs);
 
   virtual unsigned insertSyncPoint();
   virtual void signalSyncPoint(unsigned sync_point,
                                WebGraphicsSyncPointCallback* callback);
+  virtual void signalQuery(unsigned query,
+                           WebGraphicsSyncPointCallback* callback);
 
   virtual void loseContextCHROMIUM(WGC3Denum current, WGC3Denum other);
 
  protected:
   virtual GrGLInterface* onCreateGrGLInterface();
 
  private:
   WebGraphicsContext3DInProcessCommandBufferImpl(
       const WebKit::WebGraphicsContext3D::Attributes& attributes,
       bool is_offscreen,
@@ skipping 39 matching lines @@
   void FlipVertically(uint8* framebuffer,
                       unsigned int width,
                       unsigned int height);
 };
 
 }  // namespace gpu
 }  // namespace webkit
 
 #endif  // defined(ENABLE_GPU)
 #endif  // WEBKIT_COMMON_GPU_WEBGRAPHICSCONTEXT3D_IN_PROCESS_COMMAND_BUFFER_IMPL_H_