Allow MimeHandlerViewGuest be embedded inside OOPIFs

components/guest_view/browser/guest_view_manager.h

Index: components/guest_view/browser/guest_view_manager.h
diff --git a/components/guest_view/browser/guest_view_manager.h b/components/guest_view/browser/guest_view_manager.h
index 033e2a2cd1bc044412f85871708345a1728f757e..651cfaf48d9f5b93000764ff6573abdc714ea378 100644
--- a/components/guest_view/browser/guest_view_manager.h
+++ b/components/guest_view/browser/guest_view_manager.h
@@ -62,10 +62,12 @@ class GuestViewManager : public content::BrowserPluginGuestManager,
       int guest_instance_id,
       int embedder_render_process_id);
 
-  // Associates the Browser Plugin with |element_instance_id| to a
-  // guest that has ID of |guest_instance_id| and sets initialization
-  // parameters, |params| for it.
+  // Associates the Browser Plugin with |element_instance_id| to a guest that
+  // has ID of |guest_instance_id| and sets initialization parameters, |params|
+  // for it. The embedder frame is identified by the pair of
+  // |embedder_process_id| and |embedder_routing_id|.
   void AttachGuest(int embedder_process_id,
+                   int embedder_routing_id,
                    int element_instance_id,
                    int guest_instance_id,
                    const base::DictionaryValue& attach_params);
@@ -266,6 +268,12 @@ class GuestViewManager : public content::BrowserPluginGuestManager,
   using CallbacksForEachEmbedderID = std::map<int, CallbacksForEachViewID>;
   CallbacksForEachEmbedderID view_destruction_callback_map_;
 
+  // The routing ID of the embedder which most recently sent an attach request.
+  // We use this value to later identify the RenderFrameHost and WebContents
+  // which embed the guest. This is mainly used for MimeHandlerViewGuest and
+  // specifically when the guest is embedded inside a cross origin frame.
+  int attaching_guest_embedder_routing_id_;

[Charlie Reis, 2016/10/18 22:52:20]

Routing IDs can only be used in conjunction with a process ID-- they're not safe
otherwise, since they can conflict with routing IDs from another process.  Where
is the process ID corresponding to this?

[EhsanK, 2016/10/20 21:41:17]

It comes later when the attach request arrives (which also provides this
routing_id). But it is removed in the newest patch.

I needed this to pair up the routing ID with the process ID of the frame sending
the message. I noticed that there is a better place to do this where both ids
come together and we already use it to create the MimeHandlerViewGuest. I have
left a comment there (in extensions_guest_view_message_filter.cc).

+
   // This is used to ensure that an EmbedderRenderProcessHostObserver will not
   // call into this GuestViewManager after it has been destroyed.
   base::WeakPtrFactory<GuestViewManager> weak_ptr_factory_;