Pull in various gpu/command_buffer fixes from chromium

ui/gl/gpu_timing.h

 // Copyright (c) 2015 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 UI_GL_GPU_TIMING_H_
 #define UI_GL_GPU_TIMING_H_
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/gl/gl_export.h"
@@ skipping 58 matching lines @@
   uint32_t disjoint_counter_ = 0;
   DISALLOW_COPY_AND_ASSIGN(GPUTiming);
 };
 
 // Class to compute the amount of time it takes to fully
 // complete a set of GL commands
 class GL_EXPORT GPUTimer {
  public:
   ~GPUTimer();
 
+  // Destroy the timer object. This must be explicitly called before destroying
+  // this object.
+  void Destroy(bool have_context);
+
   void Start();
   void End();
   bool IsAvailable();
 
   void GetStartEndTimestamps(int64* start, int64* end);
   int64 GetDeltaElapsed();
 
  private:
   friend class GPUTimingClient;
 
@@ skipping 46 matching lines @@
   uint32_t disjoint_counter_ = 0;
   bool offset_valid_ = false;
   base::Callback<int64(void)> cpu_time_for_testing_;
 
   DISALLOW_COPY_AND_ASSIGN(GPUTimingClient);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GPU_TIMING_H_