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

components/guest_view/browser/guest_view_message_filter.h

Index: components/guest_view/browser/guest_view_message_filter.h
diff --git a/components/guest_view/browser/guest_view_message_filter.h b/components/guest_view/browser/guest_view_message_filter.h
index 163945b68876c7dae88b0ae49bd0bb88dcd512b6..9170a12cc71cdc5cf0882ed6b241f1102060ad8e 100644
--- a/components/guest_view/browser/guest_view_message_filter.h
+++ b/components/guest_view/browser/guest_view_message_filter.h
@@ -25,6 +25,7 @@ class Size;
 }
 
 namespace guest_view {
+class GuestViewBase;
 class GuestViewManager;
 
 // This class filters out incoming GuestView-specific IPC messages from the
@@ -69,9 +70,15 @@ class GuestViewMessageFilter : public content::BrowserMessageFilter {
   void OnAttachGuest(int element_instance_id,
                      int guest_instance_id,
                      const base::DictionaryValue& attach_params);
+  void OnAttachToEmbedderFrame(int embedder_local_render_frame_id,
+                               int element_instance_id,
+                               int guest_instance_id,
+                               const base::DictionaryValue& params);
   void OnViewCreated(int view_instance_id, const std::string& view_type);
   void OnViewGarbageCollected(int view_instance_id);
 
+  void WillAttachCallback(GuestViewBase* guest);
+
   DISALLOW_COPY_AND_ASSIGN(GuestViewMessageFilter);
 };