cc:: Add LatencyQuery logic back into OutputSurface.

cc/output/output_surface.h

 // Copyright 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.
 
 #ifndef CC_OUTPUT_OUTPUT_SURFACE_H_
 #define CC_OUTPUT_OUTPUT_SURFACE_H_
 
 #include <deque>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/weak_ptr.h"
 #include "cc/base/cc_export.h"
+#include "cc/base/rolling_time_delta_history.h"
 #include "cc/output/context_provider.h"
 #include "cc/output/overlay_candidate_validator.h"
 #include "cc/output/software_output_device.h"
 
 namespace base { class SingleThreadTaskRunner; }
 
 namespace ui { struct LatencyInfo; }
 
 namespace gfx {
 class Rect;
@@ skipping 95 matching lines @@
   // processing should be stopped, or lowered in priority.
   virtual void UpdateSmoothnessTakesPriority(bool prefer_smoothness) {}
 
   // Requests a BeginFrame notification from the output surface. The
   // notification will be delivered by calling
   // OutputSurfaceClient::BeginFrame until the callback is disabled.
   virtual void SetNeedsBeginFrame(bool enable) {}
 
   bool HasClient() { return !!client_; }
 
+  // Returns an estimate of the current GPU latency. When only a software
+  // device is present, returns 0.
+  base::TimeDelta GpuLatencyEstimate();
+
   // Get the class capable of informing cc of hardware overlay capability.
   OverlayCandidateValidator* overlay_candidate_validator() const {
     return overlay_candidate_validator_.get();
   }
 
  protected:
   OutputSurfaceClient* client_;
 
   // Synchronously initialize context3d and enter hardware mode.
   // This can only supported in threaded compositing mode.
@@ skipping 22 matching lines @@
       const gfx::Rect& viewport,
       const gfx::Rect& clip,
       const gfx::Rect& viewport_rect_for_tile_priority,
       const gfx::Transform& transform_for_tile_priority,
       bool resourceless_software_draw);
 
  private:
   void SetUpContext3d();
   void ResetContext3d();
   void SetMemoryPolicy(const ManagedMemoryPolicy& policy);
+  void UpdateAndMeasureGpuLatency();
 
   bool external_stencil_test_enabled_;
 
   base::WeakPtrFactory<OutputSurface> weak_ptr_factory_;
 
+  std::deque<unsigned> available_gpu_latency_query_ids_;
+  std::deque<unsigned> pending_gpu_latency_query_ids_;
+  RollingTimeDeltaHistory gpu_latency_history_;
+
   DISALLOW_COPY_AND_ASSIGN(OutputSurface);
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_OUTPUT_SURFACE_H_