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

ui/views/controls/label.h

Index: ui/views/controls/label.h
diff --git a/ui/views/controls/label.h b/ui/views/controls/label.h
index 2321242a11f48e9a98146f6759b381938c4f7ba1..152058b2b884e0f368edcc2a5d888ac6bc55bd64 100644
--- a/ui/views/controls/label.h
+++ b/ui/views/controls/label.h
@@ -191,7 +191,7 @@ class VIEWS_EXPORT Label : public View {
  protected:
   // Called by Paint to paint the text.  Override this to change how
   // text is painted.
-  virtual void PaintText(gfx::Canvas* canvas,
+  virtual void PaintText(gfx::CanvasSkia* canvas,
                          const string16& text,
                          const gfx::Rect& text_bounds,
                          int flags);
@@ -205,10 +205,10 @@ class VIEWS_EXPORT Label : public View {
   // Overridden from View:
   // Overridden to dirty our text bounds if we're multi-line.
   virtual void OnBoundsChanged(const gfx::Rect& previous_bounds) OVERRIDE;
-  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
+  virtual void OnPaint(gfx::CanvasSkia* canvas) OVERRIDE;
   // If the mouse is over the label, and a mouse over background has been
   // specified, its used. Otherwise super's implementation is invoked.
-  virtual void OnPaintBackground(gfx::Canvas* canvas) OVERRIDE;
+  virtual void OnPaintBackground(gfx::CanvasSkia* canvas) OVERRIDE;
 
  private:
   // These tests call CalculateDrawStringParams in order to verify the