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

cc/input/input_handler.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_INPUT_INPUT_HANDLER_H_
 #define CC_INPUT_INPUT_HANDLER_H_
 
 #include "base/basictypes.h"
 #include "base/time/time.h"
 #include "cc/base/cc_export.h"
@@ skipping 67 matching lines @@
   // scrolling layer's (logical pixel) space. If there is no room to move the
   // layer in the requested direction, its first ancestor layer that can be
   // scrolled will be moved instead. If no layer can be moved in the requested
   // direction at all, then false is returned. If any layer is moved, then
   // true is returned.
   // If the scroll delta hits the root layer, and the layer can no longer move,
   // the root overscroll accumulated within this ScrollBegin() scope is reported
   // to the client.
   // Should only be called if ScrollBegin() returned ScrollStarted.
   virtual bool ScrollBy(gfx::Point viewport_point,
-                        gfx::Vector2dF scroll_delta) = 0;
+                        const gfx::Vector2dF& scroll_delta) = 0;
 
   virtual bool ScrollVerticallyByPage(
       gfx::Point viewport_point,
       ScrollDirection direction) = 0;
 
   // Returns ScrollStarted if a layer was being actively being scrolled,
   // ScrollIgnored if not.
   virtual ScrollStatus FlingScrollBegin() = 0;
 
-  virtual void NotifyCurrentFlingVelocity(gfx::Vector2dF velocity) = 0;
+  virtual void NotifyCurrentFlingVelocity(const gfx::Vector2dF& velocity) = 0;
 
   virtual void MouseMoveAt(gfx::Point mouse_position) = 0;
 
   // Stop scrolling the selected layer. Should only be called if ScrollBegin()
   // returned ScrollStarted.
   virtual void ScrollEnd() = 0;
 
   virtual void SetRootLayerScrollOffsetDelegate(
       LayerScrollOffsetDelegate* root_layer_scroll_offset_delegate) = 0;
 
@@ skipping 30 matching lines @@
   InputHandler() {}
   virtual ~InputHandler() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(InputHandler);
 };
 
 }  // namespace cc
 
 #endif  // CC_INPUT_INPUT_HANDLER_H_