Generalize layer mirroring for phantom windows

chrome/browser/ui/views/frame/contents_web_view.cc

 // Copyright 2014 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 "chrome/browser/ui/views/frame/contents_web_view.h"
 
 #include "chrome/browser/themes/theme_properties.h"
 #include "chrome/browser/ui/views/status_bubble_views.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
@@ skipping 74 matching lines @@
   // in effect. The animation cloned our layer, but it won't create another
   // clone of the WebContents layer (|cloned_layer_tree_|). Another clone
   // is not created as the clone has no owner (see CloneChildren()). Because we
   // want the WebContents layer clone to be animated we move it to the
   // old_layer, which is the layer the animation happens on. This animation ends
   // up owning the layer (and all its descendants).
   old_layer->Add(cloned_layer_tree_->release());
   cloned_layer_tree_.reset();
 }
 
+void ContentsWebView::OnLayerMirrored(ui::Layer* mirror) {
+  NOTREACHED();
+}
+
 void ContentsWebView::CloneWebContentsLayer() {
   if (!web_contents())
     return;
 #if defined(USE_AURA)
   // We don't need to clone the layers on non-Aura (Mac), because closing an
   // NSWindow does not animate.
   cloned_layer_tree_ =
       wm::RecreateLayers(web_contents()->GetNativeView(), nullptr);
 #endif
   if (!cloned_layer_tree_ || !cloned_layer_tree_->root()) {
@@ skipping 18 matching lines @@
   cloned_layer_tree_.reset();
   SetPaintToLayer(false);
   set_layer_owner_delegate(nullptr);
 }
 
 void ContentsWebView::RenderViewReady() {
   // Apply the theme color to be the default background on startup.
   OnThemeChanged();
   WebView::RenderViewReady();
 }