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

extensions/renderer/guest_view/extensions_guest_view_container.h

Index: extensions/renderer/guest_view/extensions_guest_view_container.h
diff --git a/extensions/renderer/guest_view/extensions_guest_view_container.h b/extensions/renderer/guest_view/extensions_guest_view_container.h
index 75e21698d9d35c9847b71182a6efd4631f9b53af..a55d8b601a19782a033beef6126546811ceafb41 100644
--- a/extensions/renderer/guest_view/extensions_guest_view_container.h
+++ b/extensions/renderer/guest_view/extensions_guest_view_container.h
@@ -70,6 +70,20 @@ class ExtensionsGuestViewContainer : public GuestViewContainer {
     scoped_ptr<base::DictionaryValue> params_;
   };
 
+  class AttachIframeRequest : public Request {
+   public:
+    AttachIframeRequest(GuestViewContainer* container,
+                        int guest_instance_id,
+                        v8::Handle<v8::Function> callback,
+                        v8::Isolate* isolate);
+    ~AttachIframeRequest() override;
+
+    void PerformRequest() override;
+    void HandleResponse(const IPC::Message& message) override;
+   private:
+    const int guest_instance_id_;
+  };
+
   class DetachRequest : public Request {
    public:
     DetachRequest(GuestViewContainer* container,
@@ -92,6 +106,8 @@ class ExtensionsGuestViewContainer : public GuestViewContainer {
   void RegisterElementResizeCallback(v8::Handle<v8::Function> callback,
                                      v8::Isolate* isolate);
 
+  void GuestContentWindowReady(const IPC::Message& message);
+
   // BrowserPluginDelegate implementation.
   bool OnMessageReceived(const IPC::Message& message) override;
   void SetElementInstanceID(int element_instance_id) override;