cc: Record frame timing composite events in the tracker.

cc/debug/frame_timing_request.h

 // Copyright 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 CC_DEBUG_FRAME_TIMING_REQUEST_H_
 #define CC_DEBUG_FRAME_TIMING_REQUEST_H_
 
 #include "ui/gfx/geometry/rect.h"
 
 namespace cc {
 
 // This class represents a request to record frame timing information about the
 // given rect (in layer space) and an associated request id. When this request
 // is propagated to the active LayerImpl, it will cause events to be saved in
 // FrameTimingTracker, which in turn can be consumed by the requester.
 class FrameTimingRequest {
  public:
   FrameTimingRequest();
   FrameTimingRequest(int64_t request_id, const gfx::Rect& rect);
 
+  // Return the ID for the request.
   int64_t id() const { return id_; }
+
+  // Return the layer space rect for this request.
   const gfx::Rect& rect() const { return rect_; }
 
  private:
   int64_t id_;
   gfx::Rect rect_;
 };
 
 }  // namespace cc
 
 #endif  // CC_DEBUG_FRAME_TIMING_REQUEST_H_