Refactor the PlatformContext layer to have only one class.

views/widget/root_view_win.cc

 // Copyright (c) 2006-2008 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 "views/widget/root_view.h"
 
 #include "app/drag_drop_types.h"
-#include "app/gfx/canvas.h"
+#include "app/gfx/canvas_paint.h"
 #include "base/base_drag_source.h"
 #include "base/logging.h"
 #include "views/widget/root_view_drop_target.h"
 
 namespace views {
 
 void RootView::OnPaint(HWND hwnd) {
   gfx::Rect original_dirty_region = GetScheduledPaintRectConstrainedToSize();
   if (!original_dirty_region.IsEmpty()) {
     // Invoke InvalidateRect so that the dirty region of the window includes the
@@ skipping 25 matching lines @@
   // If the view is removed during the drag operation, drag_view_ is set to
   // NULL.
   if (drag_view_ == view) {
     View* drag_view = drag_view_;
     drag_view_ = NULL;
     drag_view->OnDragDone();
   }
 }
 
 }