Added support for Time Elapsed queries through the command buffer.

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 <queue>
 
 #include "base/callback.h"
@@ skipping 68 matching lines @@
 class GL_EXPORT GPUTimer {
  public:
   static void DisableTimestampQueries();
 
   ~GPUTimer();
 
   // Destroy the timer object. This must be explicitly called before destroying
   // this object.
   void Destroy(bool have_context);
 
-  // Start an instant timer, start and end will be equal.
-  void Instant();
-
   // Start a timer range.
   void Start();
   void End();
 
   bool IsAvailable();
 
   void GetStartEndTimestamps(int64* start, int64* end);
   int64 GetDeltaElapsed();
 
  private:
@@ skipping 46 matching lines @@
   GPUTimingImpl* gpu_timing_;
   GPUTiming::TimerType timer_type_ = GPUTiming::kTimerTypeInvalid;
   uint32_t disjoint_counter_ = 0;
 
   DISALLOW_COPY_AND_ASSIGN(GPUTimingClient);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GL_GPU_TIMING_H_