[#5] Pass gfx structs by const ref (gfx::Vector2dF)

cc/trees/layer_tree_host_impl.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_IMPL_H_
 #define CC_TREES_LAYER_TREE_HOST_IMPL_H_
 
 #include <list>
 #include <set>
 #include <string>
@@ skipping 96 matching lines @@
       SharedBitmapManager* manager,
       int id);
   virtual ~LayerTreeHostImpl();
 
   // InputHandler implementation
   virtual void BindToClient(InputHandlerClient* client) OVERRIDE;
   virtual InputHandler::ScrollStatus ScrollBegin(
       gfx::Point viewport_point,
       InputHandler::ScrollInputType type) OVERRIDE;
   virtual bool ScrollBy(gfx::Point viewport_point,
-                        gfx::Vector2dF scroll_delta) OVERRIDE;
+                        const gfx::Vector2dF& scroll_delta) OVERRIDE;
   virtual bool ScrollVerticallyByPage(gfx::Point viewport_point,
                                       ScrollDirection direction) OVERRIDE;
   virtual void SetRootLayerScrollOffsetDelegate(
       LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) OVERRIDE;
   virtual void OnRootLayerDelegatedScrollOffsetChanged() OVERRIDE;
   virtual void ScrollEnd() OVERRIDE;
   virtual InputHandler::ScrollStatus FlingScrollBegin() OVERRIDE;
-  virtual void NotifyCurrentFlingVelocity(gfx::Vector2dF velocity) OVERRIDE;
+  virtual void NotifyCurrentFlingVelocity(
+      const gfx::Vector2dF& velocity) OVERRIDE;
   virtual void MouseMoveAt(gfx::Point viewport_point) OVERRIDE;
   virtual void PinchGestureBegin() OVERRIDE;
   virtual void PinchGestureUpdate(float magnify_delta,
                                   gfx::Point anchor) OVERRIDE;
   virtual void PinchGestureEnd() OVERRIDE;
   virtual void StartPageScaleAnimation(gfx::Vector2d target_offset,
                                        bool anchor_point,
                                        float page_scale,
                                        base::TimeDelta duration) OVERRIDE;
   virtual void ScheduleAnimation() OVERRIDE;
@@ skipping 328 matching lines @@
   void EnforceZeroBudget(bool zero_budget);
 
   void AnimatePageScale(base::TimeTicks monotonic_time);
   void AnimateScrollbars(base::TimeTicks monotonic_time);
   void AnimateTopControls(base::TimeTicks monotonic_time);
 
   gfx::Vector2dF ScrollLayerWithViewportSpaceDelta(
       LayerImpl* layer_impl,
       float scale_from_viewport_to_screen_space,
       const gfx::PointF& viewport_point,
-      gfx::Vector2dF viewport_delta);
+      const gfx::Vector2dF& viewport_delta);
 
   void UpdateMaxScrollOffset();
   void TrackDamageForAllSurfaces(
       LayerImpl* root_draw_layer,
       const LayerImplList& render_surface_layer_list);
 
   void UpdateTileManagerMemoryPolicy(const ManagedMemoryPolicy& policy);
 
   // Returns false if the frame should not be displayed. This function should
   // only be called from PrepareToDraw, as DidDrawAllLayers must be called
@@ skipping 166 matching lines @@
   int id_;
 
   std::set<SwapPromiseMonitor*> swap_promise_monitor_;
 
   DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };
 
 }  // namespace cc
 
 #endif  // CC_TREES_LAYER_TREE_HOST_IMPL_H_