Added support for TimeStamp queries using QueryCounterEXT.

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 25 matching lines @@
 //   GPUTimer - Once a user decides to time something, the user creates a new
 //     GPUTimer object from a GPUTimingClient and issue Start() and Stop() calls
 //     around various GL calls. Once IsAvailable() returns true, the GPU times
 //     will be available through the various time stamp related functions.
 //     The constructor and destructor of this object handles the actual
 //     creation and deletion of the GL Queries within GL.
 
 namespace gfx {
 
 class GLContextReal;
-class GPUTiming;
 class GPUTimingClient;
 class GPUTimingImpl;
 class QueryResult;
-class TimeElapsedTimerQuery;
-class TimerQuery;
 
 class GPUTiming {
  public:
   enum TimerType {
     kTimerTypeInvalid = -1,
 
     kTimerTypeEXT,      // EXT_timer_query
     kTimerTypeARB,      // ARB_timer_query
     kTimerTypeDisjoint  // EXT_disjoint_timer_query
   };
@@ skipping 17 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);
 
+  // Clears current queries.
+  void Reset();
+
+  // Start an instant timer, start and end will be equal.
+  void QueryTimeStamp();
+
   // Start a timer range.
   void Start();
   void End();
 
   bool IsAvailable();
 
   void GetStartEndTimestamps(int64* start, int64* end);
   int64 GetDeltaElapsed();
 
  private:
   friend class GPUTimingClient;
 
   explicit GPUTimer(scoped_refptr<GPUTimingClient> gpu_timing_client,
                     bool use_elapsed_timer);
 
   bool use_elapsed_timer_ = false;
-  bool end_requested_ = false;
-  bool end_available_ = false;
+  enum TimerState {
+    kTimerState_Ready,
+    kTimerState_WaitingForEnd,
+    kTimerState_WaitingForResult,
+    kTimerState_ResultAvailable
+  } timer_state_ = kTimerState_Ready;
   scoped_refptr<GPUTimingClient> gpu_timing_client_;
   scoped_refptr<QueryResult> time_stamp_result_;
   scoped_refptr<QueryResult> elapsed_timer_result_;
 
   DISALLOW_COPY_AND_ASSIGN(GPUTimer);
 };
 
 // GPUTimingClient contains all the gl timing logic that is not specific
 // to a single GPUTimer.
 class GL_EXPORT GPUTimingClient
@@ skipping 28 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_