Pass a ui::PaintContext from ui::Layer to layer delegates.

ash/root_window_controller.cc

 // 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.
 
 #include "ash/root_window_controller.h"
 
 #include <queue>
 #include <vector>
 
 #include "ash/ash_constants.h"
@@ skipping 217 matching lines @@
   int GetNonClientComponent(const gfx::Point& point) const override {
     return HTNOWHERE;
   }
   bool ShouldDescendIntoChildForEventHandling(
       aura::Window* child,
       const gfx::Point& location) override {
     return false;
   }
   bool CanFocus() override { return false; }
   void OnCaptureLost() override {}
-  void OnPaint(gfx::Canvas* canvas) override {}
+  void OnPaint(const ui::PaintContext& context) override {}
   void OnDeviceScaleFactorChanged(float device_scale_factor) override {}
   void OnWindowDestroying(aura::Window* window) override {}
   void OnWindowDestroyed(aura::Window* window) override { delete this; }
   void OnWindowTargetVisibilityChanged(bool visible) override {}
   bool HasHitTestMask() const override { return false; }
   void GetHitTestMask(gfx::Path* mask) const override {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(EmptyWindowDelegate);
 };
@@ skipping 806 matching lines @@
   else
     DisableTouchHudProjection();
 }
 
 RootWindowController* GetRootWindowController(
     const aura::Window* root_window) {
   return root_window ? GetRootWindowSettings(root_window)->controller : NULL;
 }
 
 }  // namespace ash