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

ui/views/widget/widget.h

 // 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.
 
 #ifndef UI_VIEWS_WIDGET_WIDGET_H_
 #define UI_VIEWS_WIDGET_WIDGET_H_
 
 #include <set>
 #include <stack>
 #include <vector>
@@ skipping 777 matching lines @@
   void OnNativeWidgetDestroyed() override;
   gfx::Size GetMinimumSize() const override;
   gfx::Size GetMaximumSize() const override;
   void OnNativeWidgetMove() override;
   void OnNativeWidgetSizeChanged(const gfx::Size& new_size) override;
   void OnNativeWidgetWindowShowStateChanged() override;
   void OnNativeWidgetBeginUserBoundsChange() override;
   void OnNativeWidgetEndUserBoundsChange() override;
   bool HasFocusManager() const override;
   bool OnNativeWidgetPaintAccelerated(const gfx::Rect& dirty_region) override;
-  void OnNativeWidgetPaint(gfx::Canvas* canvas) override;
+  void OnNativeWidgetPaint(const ui::PaintContext& context) override;
   int GetNonClientComponent(const gfx::Point& point) override;
   void OnKeyEvent(ui::KeyEvent* event) override;
   void OnMouseEvent(ui::MouseEvent* event) override;
   void OnMouseCaptureLost() override;
   void OnScrollEvent(ui::ScrollEvent* event) override;
   void OnGestureEvent(ui::GestureEvent* event) override;
   bool ExecuteCommand(int command_id) override;
   InputMethod* GetInputMethodDirect() override;
   const std::vector<ui::Layer*>& GetRootLayers() override;
   bool HasHitTestMask() const override;
@@ skipping 170 matching lines @@
   bool movement_disabled_;
 
   ScopedObserver<ui::NativeTheme, ui::NativeThemeObserver> observer_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(Widget);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_WIDGET_H_