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

webkit/common/gpu/webgraphicscontext3d_in_process_command_buffer_impl.cc

 // 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.
 
 #include "webkit/common/gpu/webgraphicscontext3d_in_process_command_buffer_impl.h"
 
 #include <GLES2/gl2.h>
 #ifndef GL_GLEXT_PROTOTYPES
 #define GL_GLEXT_PROTOTYPES 1
 #endif
@@ skipping 1945 matching lines @@
 
 void WebGraphicsContext3DInProcessCommandBufferImpl::signalSyncPoint(
     unsigned sync_point,
     WebGraphicsSyncPointCallback* callback) {
   // Take ownership of the callback.
   context_->SetSignalSyncPointCallback(make_scoped_ptr(callback));
   // Stick something in the command buffer.
   shallowFlushCHROMIUM();
 }
 
+void WebGraphicsContext3DInProcessCommandBufferImpl::signalQuery(
+    unsigned query,
+    WebGraphicsSyncPointCallback* callback) {
+  finish();
+  // Take ownership of the callback.
+  context_->SetSignalSyncPointCallback(make_scoped_ptr(callback));
+  // Stick something in the command buffer.
+  shallowFlushCHROMIUM();
+}
+
 void WebGraphicsContext3DInProcessCommandBufferImpl::loseContextCHROMIUM(
     WGC3Denum current, WGC3Denum other) {
   context_->LoseContext(current, other);
 }
 
 DELEGATE_TO_GL_9(asyncTexImage2DCHROMIUM, AsyncTexImage2DCHROMIUM,
     WGC3Denum, WGC3Dint, WGC3Denum, WGC3Dsizei, WGC3Dsizei, WGC3Dint,
     WGC3Denum, WGC3Denum, const void*)
 
 DELEGATE_TO_GL_9(asyncTexSubImage2DCHROMIUM, AsyncTexSubImage2DCHROMIUM,
     WGC3Denum, WGC3Dint, WGC3Dint, WGC3Dint, WGC3Dsizei, WGC3Dsizei,
     WGC3Denum, WGC3Denum, const void*)
 
 DELEGATE_TO_GL_1(waitAsyncTexImage2DCHROMIUM, WaitAsyncTexImage2DCHROMIUM,
     WGC3Denum)
 
 void WebGraphicsContext3DInProcessCommandBufferImpl::SetGpuMemoryBufferCreator(
     GpuMemoryBufferCreator* creator) {
   g_gpu_memory_buffer_creator = creator;
 }
 
 }  // namespace gpu
 }  // namespace webkit