Mandoline: fix the crash when a remote subframe tries to access session storage.

components/html_viewer/html_widget.h

 // Copyright 2015 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 COMPONENTS_HTML_VIEWER_HTML_WIDGET_H_
 #define COMPONENTS_HTML_VIEWER_HTML_WIDGET_H_
 
 #include "third_party/WebKit/public/web/WebViewClient.h"
 #include "third_party/WebKit/public/web/WebWidgetClient.h"
 
@@ skipping 20 matching lines @@
 class HTMLWidget {
  public:
   virtual ~HTMLWidget() {}
 
   virtual blink::WebWidget* GetWidget() = 0;
 
   virtual void OnViewBoundsChanged(mus::View* view) = 0;
 };
 
 // Used for the root frame when the root frame is remote.
-class HTMLWidgetRootRemote : public HTMLWidget {
+class HTMLWidgetRootRemote : public HTMLWidget, public blink::WebViewClient {
  public:
   HTMLWidgetRootRemote();
   ~HTMLWidgetRootRemote() override;
 
  private:
+  // WebViewClient methods:
+  virtual blink::WebStorageNamespace* createSessionStorageNamespace();
+  virtual bool allowsBrokenNullLayerTreeView() const;
+
   // HTMLWidget:
   blink::WebWidget* GetWidget() override;
   void OnViewBoundsChanged(mus::View* view) override;
 
   blink::WebView* web_view_;
 
   DISALLOW_COPY_AND_ASSIGN(HTMLWidgetRootRemote);
 };
 
 // Used for the root frame when the frame is local. If there is only one
@@ skipping 71 matching lines @@
   blink::WebFrameWidget* web_frame_widget_;
   scoped_ptr<WebLayerTreeViewImpl> web_layer_tree_view_impl_;
   scoped_ptr<ImeController> ime_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(HTMLWidgetLocalRoot);
 };
 
 }  // namespace html_viewer
 
 #endif  // COMPONENTS_HTML_VIEWER_HTML_WIDGET_H_