ui: Introduce CanvasPainter, remove PaintContext(gfx::Canvas*).

ui/views/widget/desktop_aura/desktop_window_tree_host_win.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_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_WIN_H_
 #define UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_WIN_H_
 
 #include "ui/aura/window_tree_host.h"
 #include "ui/views/views_export.h"
 #include "ui/views/widget/desktop_aura/desktop_window_tree_host.h"
@@ skipping 129 matching lines @@
   bool WidgetSizeIsClientSize() const override;
   bool IsModal() const override;
   int GetInitialShowState() const override;
   bool WillProcessWorkAreaChange() const override;
   int GetNonClientComponent(const gfx::Point& point) const override;
   void GetWindowMask(const gfx::Size& size, gfx::Path* path) override;
   bool GetClientAreaInsets(gfx::Insets* insets) const override;
   void GetMinMaxSize(gfx::Size* min_size, gfx::Size* max_size) const override;
   gfx::Size GetRootViewSize() const override;
   void ResetWindowControls() override;
-  void PaintLayeredWindow(gfx::Canvas* canvas) override;
   gfx::NativeViewAccessible GetNativeViewAccessible() override;
   bool ShouldHandleSystemCommands() const override;
   InputMethod* GetInputMethod() override;
   void HandleAppDeactivated() override;
   void HandleActivationChanged(bool active) override;
   bool HandleAppCommand(short command) override;
   void HandleCancelMode() override;
   void HandleCaptureLost() override;
   void HandleClose() override;
   bool HandleCommand(int command) override;
@@ skipping 97 matching lines @@
   static bool is_cursor_visible_;
 
   scoped_ptr<aura::client::ScopedTooltipDisabler> tooltip_disabler_;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopWindowTreeHostWin);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_DESKTOP_AURA_DESKTOP_WINDOW_TREE_HOST_WIN_H_