Pass const gfx::Rect& as the first parameter to FillRect.

ui/gfx/canvas.h

 // Copyright (c) 2012 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 UI_GFX_CANVAS_H_
 #define UI_GFX_CANVAS_H_
 #pragma once
 
 #include <string>
 
@@ skipping 87 matching lines @@
   // call Restore() more times than Save*().
   virtual void Restore() = 0;
 
   // Returns true if the clip is non-empty.
   virtual bool ClipRect(const gfx::Rect& rect) = 0;
 
   virtual void Translate(const gfx::Point& point) = 0;
 
   virtual void Scale(int x_scale, int y_scale) = 0;
 
-  // Fills the specified region with the specified color using a transfer
-  // mode of SkXfermode::kSrcOver_Mode.
-  virtual void FillRect(const SkColor& color, const gfx::Rect& rect) = 0;
+  // Fills |rect| with |color| using a transfer mode of
+  // SkXfermode::kSrcOver_Mode.
+  virtual void FillRect(const gfx::Rect& rect, const SkColor& color) = 0;
 
-  // Fills the specified region with the specified color and mode.
-  virtual void FillRect(const SkColor& color,
-                        const gfx::Rect& rect,
+  // Fills |rect| with the specified |color| and |mode|.
+  virtual void FillRect(const gfx::Rect& rect,
+                        const SkColor& color,
                         SkXfermode::Mode mode) = 0;
 
-  // Fills the specified region with the specified brush.
-  virtual void FillRect(const gfx::Brush* brush, const gfx::Rect& rect) = 0;
+  // Fills |rect| with the specified |brush|.
+  virtual void FillRect(const gfx::Rect& rect, const gfx::Brush* brush) = 0;
 
   // Draws a single pixel rect in the specified region with the specified
   // color, using a transfer mode of SkXfermode::kSrcOver_Mode.
   //
   // NOTE: if you need a single pixel line, use DrawLineInt.
   virtual void DrawRect(const gfx::Rect& rect, const SkColor& color) = 0;
 
   // Draws a single pixel rect in the specified region with the specified
   // color and transfer mode.
   //
@@ skipping 108 matching lines @@
   // Returns the rectangle that is invalid.
   virtual gfx::Rect GetInvalidRect() const = 0;
 
   // Returns the underlying Canvas.
   virtual Canvas* AsCanvas() = 0;
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_CANVAS_H_