WIP: Plumbing input event latency reporting through Mus GPU.

services/ui/surfaces/display_output_surface.h

Index: services/ui/surfaces/display_output_surface.h
diff --git a/services/ui/surfaces/display_output_surface.h b/services/ui/surfaces/display_output_surface.h
index 0861c1d7bbe1a3baaa2bd52965f7df687b4a500e..076a8fa7bca326dced0ad89ad7102cddc1b9f11f 100644
--- a/services/ui/surfaces/display_output_surface.h
+++ b/services/ui/surfaces/display_output_surface.h
@@ -14,6 +14,10 @@ namespace cc {
 class SyntheticBeginFrameSource;
 }
 
+namespace latency_tracker {
+class LatencyTracker;
+}
+
 namespace ui {
 
 // An OutputSurface implementation that directly draws and
@@ -52,6 +56,10 @@ class DisplayOutputSurface : public cc::OutputSurface {
   virtual void DidReceiveSwapBuffersAck(gfx::SwapResult result);
 
  private:
+  cc::InProcessContextProvider* in_process_context_provider() {

[mfomitchev, 2017/03/24 20:55:58]

How about this?

+    return static_cast<cc::InProcessContextProvider*>(context_provider());
+  }
+
   // Called when a swap completion is signaled from ImageTransportSurface.
   void OnGpuSwapBuffersCompleted(
       const std::vector<ui::LatencyInfo>& latency_info,
@@ -62,6 +70,8 @@ class DisplayOutputSurface : public cc::OutputSurface {
 
   cc::OutputSurfaceClient* client_ = nullptr;
   cc::SyntheticBeginFrameSource* const synthetic_begin_frame_source_;
+  std::unique_ptr<latency_tracker::LatencyTracker> latency_tracker_;
+
   bool set_draw_rectangle_for_frame_ = false;
   // True if the draw rectangle has been set at all since the last resize.
   bool has_set_draw_rectangle_since_last_resize_ = false;