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

ui/views/controls/tree/tree_view_views.h

Index: ui/views/controls/tree/tree_view_views.h
diff --git a/ui/views/controls/tree/tree_view_views.h b/ui/views/controls/tree/tree_view_views.h
index e97fcd62ba6e05a47d6b744c276f9ad713b8ae64..2b3b96c0686003da4f5617d0e66f690beb488445 100644
--- a/ui/views/controls/tree/tree_view_views.h
+++ b/ui/views/controls/tree/tree_view_views.h
@@ -141,7 +141,7 @@ class VIEWS_EXPORT TreeView : public View,
   // View overrides:
   virtual gfx::Point GetKeyboardContextMenuLocation() OVERRIDE;
   virtual bool OnKeyPressed(const KeyEvent& event) OVERRIDE;
-  virtual void OnPaint(gfx::Canvas* canvas) OVERRIDE;
+  virtual void OnPaint(gfx::CanvasSkia* canvas) OVERRIDE;
   virtual void OnFocus() OVERRIDE;
   virtual void OnBlur() OVERRIDE;
 
@@ -245,7 +245,7 @@ class VIEWS_EXPORT TreeView : public View,
   // Recursively paints rows from |min_row| to |max_row|. |node| is the node for
   // the row |*row|. |row| is updated as this walks the tree. Depth is the depth
   // of |*row|.
-  void PaintRows(gfx::Canvas* canvas,
+  void PaintRows(gfx::CanvasSkia* canvas,
                  int min_row,
                  int max_row,
                  InternalNode* node,
@@ -253,13 +253,13 @@ class VIEWS_EXPORT TreeView : public View,
                  int* row);
 
   // Invoked to paint a single node.
-  void PaintRow(gfx::Canvas* canvas,
+  void PaintRow(gfx::CanvasSkia* canvas,
                 InternalNode* node,
                 int row,
                 int depth);
 
   // Paints the expand control given the specified nodes bounds.
-  void PaintExpandControl(gfx::Canvas* canvas,
+  void PaintExpandControl(gfx::CanvasSkia* canvas,
                           const gfx::Rect& node_bounds,
                           bool expanded);