layers: Consolidate the ownership of layers in views::View and aura::Window.

ui/views/view.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_VIEW_H_
 #define UI_VIEWS_VIEW_H_
 #pragma once
 
 #include <algorithm>
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/i18n/rtl.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "build/build_config.h"
 #include "ui/base/accelerators/accelerator.h"
 #include "ui/base/dragdrop/os_exchange_data.h"
 #include "ui/compositor/layer_delegate.h"
+#include "ui/compositor/layer_owner.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/gfx/rect.h"
 #include "ui/views/background.h"
 #include "ui/views/border.h"
 #include "ui/views/events/event.h"
 
 #if defined(OS_WIN)
 #include "base/win/scoped_comptr.h"
 #endif
 
@@ skipping 56 matching lines @@
 //   LayoutManager interface can be used to lay out children if required.
 //
 //   It is up to the subclass to implement Painting and storage of subclass -
 //   specific properties and functionality.
 //
 //   Unless otherwise documented, views is not thread safe and should only be
 //   accessed from the main thread.
 //
 /////////////////////////////////////////////////////////////////////////////
 class VIEWS_EXPORT View : public ui::LayerDelegate,
+                          public ui::LayerOwner,
                           public ui::AcceleratorTarget {
  public:
   typedef std::vector<View*> Views;
 
   // Creation and lifetime -----------------------------------------------------
 
   View();
   virtual ~View();
 
   // By default a View is owned by its parent unless specified otherwise here.
@@ skipping 162 matching lines @@
   void SetTransform(const ui::Transform& transform);
 
   // Sets whether this view paints to a layer. A view paints to a layer if
   // either of the following are true:
   // . the view has a non-identity transform.
   // . SetPaintToLayer(true) has been invoked.
   // View creates the Layer only when it exists in a Widget with a non-NULL
   // Compositor.
   void SetPaintToLayer(bool paint_to_layer);
 
-  const ui::Layer* layer() const { return layer_.get(); }
-  ui::Layer* layer() { return layer_.get(); }
+  // Recreates a layer for the view and returns the old layer. After this call,
+  // the View no longer has a pointer to the old layer (so it won't be able to
+  // update the old layer or destroy it). The caller must free the returned
+  // layer.
+  ui::Layer* RecreateLayer() WARN_UNUSED_RESULT;
 
   // RTL positioning -----------------------------------------------------------
 
   // Methods for accessing the bounds and position of the view, relative to its
   // parent. The position returned is mirrored if the parent view is using a RTL
   // layout.
   //
   // NOTE: in the vast majority of the cases, the mirroring implementation is
   //       transparent to the View subclasses and therefore you should use the
   //       bounds() accessor instead.
@@ skipping 1112 matching lines @@
   // RTL painting --------------------------------------------------------------
 
   // Indicates whether or not the gfx::Canvas object passed to View::Paint()
   // is going to be flipped horizontally (using the appropriate transform) on
   // right-to-left locales for this View.
   bool flip_canvas_on_paint_for_rtl_ui_;
 
   // Accelerated painting ------------------------------------------------------
 
   bool paint_to_layer_;
-  scoped_ptr<ui::Layer> layer_;
 
   // Accelerators --------------------------------------------------------------
 
   // true if when we were added to hierarchy we were without focus manager
   // attempt addition when ancestor chain changed.
   bool accelerator_registration_delayed_;
 
   // Focus manager accelerators registered on.
   FocusManager* accelerator_focus_manager_;
 
@@ skipping 34 matching lines @@
   base::win::ScopedComPtr<NativeViewAccessibilityWin>
       native_view_accessibility_win_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(View);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_VIEW_H_