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

ui/aura/test/test_window_delegate.h

Index: ui/aura/test/test_window_delegate.h
diff --git a/ui/aura/test/test_window_delegate.h b/ui/aura/test/test_window_delegate.h
index 57a5ba1a8e9d9f10072c706693be70de7638c8df..091abeae7400317c5e21ab7e053357fdf0f83748 100644
--- a/ui/aura/test/test_window_delegate.h
+++ b/ui/aura/test/test_window_delegate.h
@@ -37,7 +37,7 @@ class TestWindowDelegate : public WindowDelegate {
   virtual ui::GestureStatus OnGestureEvent(GestureEvent* event) OVERRIDE;
   virtual bool CanFocus() OVERRIDE;
   virtual void OnCaptureLost() OVERRIDE;
-  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
+  virtual void OnPaint(gfx::CanvasSkia* canvas) OVERRIDE;
   virtual void OnWindowDestroying() OVERRIDE;
   virtual void OnWindowDestroyed() OVERRIDE;
   virtual void OnWindowVisibilityChanged(bool visible) OVERRIDE;
@@ -60,7 +60,7 @@ class ColorTestWindowDelegate : public TestWindowDelegate {
   // Overridden from TestWindowDelegate:
   virtual bool OnKeyEvent(KeyEvent* event) OVERRIDE;
   virtual void OnWindowDestroyed() OVERRIDE;
-  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
+  virtual void OnPaint(gfx::CanvasSkia* canvas) OVERRIDE;
 
  private:
   SkColor color_;