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

content/common/gpu/client/command_buffer_proxy_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 "content/common/gpu/client/command_buffer_proxy_impl.h"
 
 #include "base/callback.h"
 #include "base/debug/trace_event.h"
 #include "base/logging.h"
 #include "base/process_util.h"
@@ skipping 416 matching lines @@
                                                     sync_point,
                                                     signal_id))) {
     return false;
   }
 
   signal_tasks_.insert(std::make_pair(signal_id, callback));
 
   return true;
 }
 
+bool CommandBufferProxyImpl::SignalQuery(unsigned query,
+                                         const base::Closure& callback) {
+  if (last_state_.error != gpu::error::kNoError) {
+    return false;
+  }
+
+  uint32 signal_id = next_signal_id_++;
+  if (!Send(new GpuCommandBufferMsg_SignalQuery(route_id_,
+                                                query,
+                                                signal_id))) {
+    return false;
+  }
+
+  signal_tasks_.insert(std::make_pair(signal_id, callback));
+
+  return true;
+}
+
 
 bool CommandBufferProxyImpl::GenerateMailboxNames(
     unsigned num,
     std::vector<gpu::Mailbox>* names) {
   if (last_state_.error != gpu::error::kNoError)
     return false;
 
   return channel_->GenerateMailboxNames(num, names);
 }
 
@@ skipping 75 matching lines @@
 void CommandBufferProxyImpl::SendManagedMemoryStats(
     const GpuManagedMemoryStats& stats) {
   if (last_state_.error != gpu::error::kNoError)
     return;
 
   Send(new GpuCommandBufferMsg_SendClientManagedMemoryStats(route_id_,
                                                             stats));
 }
 
 }  // namespace content