[#2] Pass gfx structs by const ref (gfx::Rect, gfx::RectF)

cc/trees/layer_tree_host.h

 // Copyright 2011 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_TREES_LAYER_TREE_HOST_H_
 #define CC_TREES_LAYER_TREE_HOST_H_
 
 #include <limits>
 #include <list>
 #include <set>
@@ skipping 128 matching lines @@
     return input_handler_weak_ptr_;
   }
 
   void NotifyInputThrottledUntilCommit();
 
   void Composite(base::TimeTicks frame_begin_time);
 
   // Composites and attempts to read back the result into the provided
   // buffer. If it wasn't possible, e.g. due to context lost, will return
   // false.
-  bool CompositeAndReadback(void* pixels, gfx::Rect rect_in_device_viewport);
+  bool CompositeAndReadback(void* pixels,
+                            const gfx::Rect& rect_in_device_viewport);
 
   void FinishAllRendering();
 
   void SetDeferCommits(bool defer_commits);
 
   // Test only hook
   virtual void DidDeferCommit();
 
   int source_frame_number() const { return source_frame_number_; }
 
   void SetNeedsDisplayOnAllLayers();
 
   void CollectRenderingStats(RenderingStats* stats) const;
 
   RenderingStatsInstrumentation* rendering_stats_instrumentation() const {
     return rendering_stats_instrumentation_.get();
   }
 
   const RendererCapabilities& GetRendererCapabilities() const;
 
   void SetNeedsAnimate();
   virtual void SetNeedsUpdateLayers();
   virtual void SetNeedsCommit();
   virtual void SetNeedsFullTreeSync();
   void SetNeedsRedraw();
-  void SetNeedsRedrawRect(gfx::Rect damage_rect);
+  void SetNeedsRedrawRect(const gfx::Rect& damage_rect);
   bool CommitRequested() const;
   bool BeginMainFrameRequested() const;
 
   void SetNextCommitWaitsForActivation();
 
   void SetNextCommitForcesRedraw();
 
   void SetAnimationEvents(scoped_ptr<AnimationEventsVector> events,
                           base::Time wall_clock_time);
 
@@ skipping 262 matching lines @@
 
   ScopedPtrVector<SwapPromise> swap_promise_list_;
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHost);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_H_