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

ui/aura/window.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 "ui/aura/window.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/stl_util.h"
@@ skipping 32 matching lines @@
 Window::TestApi::TestApi(Window* window) : window_(window) {}
 
 bool Window::TestApi::OwnsLayer() const {
   return !!window_->layer_owner_.get();
 }
 
 Window::Window(WindowDelegate* delegate)
     : type_(client::WINDOW_TYPE_UNKNOWN),
       owned_by_parent_(true),
       delegate_(delegate),
-      layer_(NULL),
       parent_(NULL),
       transient_parent_(NULL),
       visible_(false),
       id_(-1),
       transparent_(false),
       user_data_(NULL),
       ignore_events_(false) {
 }
 
 Window::~Window() {
@@ skipping 95 matching lines @@
   if (layer())
     UpdateLayerName(name_);
 }
 
 void Window::SetTransparent(bool transparent) {
   // Cannot change transparent flag after the window is initialized.
   DCHECK(!layer());
   transparent_ = transparent;
 }
 
-ui::Layer* Window::AcquireLayer() {
-  return layer_owner_.release();
-}
-
 RootWindow* Window::GetRootWindow() {
   return const_cast<RootWindow*>(
       static_cast<const Window*>(this)->GetRootWindow());
 }
 
 const RootWindow* Window::GetRootWindow() const {
   return parent_ ? parent_->GetRootWindow() : NULL;
 }
 
 void Window::Show() {
@@ skipping 644 matching lines @@
   for (Windows::const_reverse_iterator it = children_.rbegin(),
            rend = children_.rend();
        it != rend; ++it) {
     Window* child = *it;
     child->PrintWindowHierarchy(depth + 1);
   }
 }
 #endif
 
 }  // namespace aura