Make <webview> use out-of-process iframe architecture.

components/guest_view/renderer/guest_view_container.h

Index: components/guest_view/renderer/guest_view_container.h
diff --git a/components/guest_view/renderer/guest_view_container.h b/components/guest_view/renderer/guest_view_container.h
index 03d860f3443eaa45fa893aac0ab7ca3db5b85363..4204db93346166f27648a4172e8004b68a66290e 100644
--- a/components/guest_view/renderer/guest_view_container.h
+++ b/components/guest_view/renderer/guest_view_container.h
@@ -50,9 +50,16 @@ class GuestViewContainer : public content::BrowserPluginDelegate {
   // Note that this should be called exactly once.
   virtual void OnDestroy() {}
 
+  // BrowserPluginGuestDelegate public implementation.
+  void SetElementInstanceID(int element_instance_id) final;
+
  protected:
   ~GuestViewContainer() override;
 
+  bool ready_;
+
+  void OnHandleCallback(const IPC::Message& message);
+
  private:
   class RenderFrameLifetimeObserver;
   friend class RenderFrameLifetimeObserver;
@@ -63,18 +70,14 @@ class GuestViewContainer : public content::BrowserPluginDelegate {
   void PerformPendingRequest();
   void HandlePendingResponseCallback(const IPC::Message& message);
 
-  void OnHandleCallback(const IPC::Message& message);
-
   // BrowserPluginDelegate implementation.
   void Ready() final;
-  void SetElementInstanceID(int element_instance_id) final;
   void DidDestroyElement() final;
 
   int element_instance_id_;
   content::RenderFrame* render_frame_;
   scoped_ptr<RenderFrameLifetimeObserver> render_frame_lifetime_observer_;
 
-  bool ready_;
   bool in_destruction_;
 
   std::deque<linked_ptr<GuestViewRequest> > pending_requests_;