ui/gfx: Make gfx::Canvas inherit from gfx::CanvasSkia.

ui/views/controls/button/text_button.h

Index: ui/views/controls/button/text_button.h
diff --git a/ui/views/controls/button/text_button.h b/ui/views/controls/button/text_button.h
index 7b1f4474b065f9e1afa563bb3e74768a35ccc0dc..8027ac10eb85a2db32feae2d9beef55ec520a1b6 100644
--- a/ui/views/controls/button/text_button.h
+++ b/ui/views/controls/button/text_button.h
@@ -56,7 +56,7 @@ class VIEWS_EXPORT TextButtonBorder : public Border {
   };
 
   void Paint(const View& view,
-             gfx::Canvas* canvas,
+             gfx::CanvasSkia* canvas,
              const BorderImageSet& set) const;
 
   void set_normal_set(const BorderImageSet& set) { normal_set_ = set; }
@@ -68,7 +68,7 @@ class VIEWS_EXPORT TextButtonBorder : public Border {
 
  private:
   // Border:
-  virtual void Paint(const View& view, gfx::Canvas* canvas) const OVERRIDE;
+  virtual void Paint(const View& view, gfx::CanvasSkia* canvas) const OVERRIDE;
   virtual void GetInsets(gfx::Insets* insets) const OVERRIDE;
 
   BorderImageSet normal_set_;
@@ -96,7 +96,7 @@ class VIEWS_EXPORT TextButtonNativeThemeBorder : public Border {
   virtual ~TextButtonNativeThemeBorder();
 
   // Implementation of Border:
-  virtual void Paint(const View& view, gfx::Canvas* canvas) const OVERRIDE;
+  virtual void Paint(const View& view, gfx::CanvasSkia* canvas) const OVERRIDE;
   virtual void GetInsets(gfx::Insets* insets) const OVERRIDE;
 
  private:
@@ -198,14 +198,14 @@ class VIEWS_EXPORT TextButtonBase : public CustomButton,
   // Paint the button into the specified canvas. If |mode| is |PB_FOR_DRAG|, the
   // function paints a drag image representation into the canvas.
   enum PaintButtonMode { PB_NORMAL, PB_FOR_DRAG };
-  virtual void PaintButton(gfx::Canvas* canvas, PaintButtonMode mode);
+  virtual void PaintButton(gfx::CanvasSkia* canvas, PaintButtonMode mode);
 
   // Overridden from View:
   virtual gfx::Size GetPreferredSize() OVERRIDE;
   virtual gfx::Size GetMinimumSize() OVERRIDE;
   virtual int GetHeightForWidth(int w) OVERRIDE;
   virtual void OnEnabledChanged() OVERRIDE;
-  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
+  virtual void OnPaint(gfx::CanvasSkia* canvas) OVERRIDE;
 
   // Returns views/TextButton.
   virtual std::string GetClassName() const OVERRIDE;
@@ -343,10 +343,11 @@ class VIEWS_EXPORT TextButton : public TextButtonBase {
   // Overridden from View:
   virtual gfx::Size GetPreferredSize() OVERRIDE;
   virtual std::string GetClassName() const OVERRIDE;
-  virtual void OnPaintFocusBorder(gfx::Canvas* canvas) OVERRIDE;
+  virtual void OnPaintFocusBorder(gfx::CanvasSkia* canvas) OVERRIDE;
 
   // Overridden from TextButtonBase:
-  virtual void PaintButton(gfx::Canvas* canvas, PaintButtonMode mode) OVERRIDE;
+  virtual void PaintButton(gfx::CanvasSkia* canvas,
+                           PaintButtonMode mode) OVERRIDE;
 
  protected:
   SkBitmap icon() const { return icon_; }
@@ -411,7 +412,7 @@ class VIEWS_EXPORT NativeTextButton : public TextButton {
   void Init();
 
   // Overridden from View:
-  virtual void OnPaintFocusBorder(gfx::Canvas* canvas) OVERRIDE;
+  virtual void OnPaintFocusBorder(gfx::CanvasSkia* canvas) OVERRIDE;
 
   // Overridden from TextButton:
   virtual void GetExtraParams(