Allow MimeHandlerViewGuest be embedded inside OOPIFs

components/guest_view/browser/guest_view_base.cc

Index: components/guest_view/browser/guest_view_base.cc
diff --git a/components/guest_view/browser/guest_view_base.cc b/components/guest_view/browser/guest_view_base.cc
index e2ffccee70d4728e19726a3b7aea8f4c93c49aaa..edcbd2f0ced6bc447893f8cbf4bce994a45a3324 100644
--- a/components/guest_view/browser/guest_view_base.cc
+++ b/components/guest_view/browser/guest_view_base.cc
@@ -20,6 +20,7 @@
 #include "content/public/browser/render_frame_host.h"
 #include "content/public/browser/render_process_host.h"
 #include "content/public/browser/render_view_host.h"
+#include "content/public/browser/render_widget_host.h"
 #include "content/public/browser/render_widget_host_view.h"
 #include "content/public/browser/web_contents.h"
 #include "content/public/common/page_zoom.h"
@@ -416,9 +417,9 @@ void GuestViewBase::DidAttach(int guest_proxy_routing_id) {
   DidAttachToEmbedder();
 
   // Inform the associated GuestViewContainer that the contentWindow is ready.
-  embedder_web_contents()->Send(new GuestViewMsg_GuestAttached(
-      element_instance_id_,
-      guest_proxy_routing_id));
+  GetEmbedderFrame()->GetView()->GetRenderWidgetHost()->Send(

[nasko, 2016/10/27 21:03:40]

Before this IPC was sent through the main frame. Now it is sent through the
widget. Is this intentional? Guest attaching doesn't strike me as a
graphics/input event type message, but I can be wrong.

[EhsanK, 2016/10/27 22:06:48]

As I understand, WebContentsImpl::Send will send its message through
RenderViewHostImpl which will send it through RenderWidgetHostImpl (of the
page?). That is why I transferred it to RenderWidgetHost here.

Also, this IPC specifically is handled by a GuestViewContainerDispatcher which
is a RenderThreadObserver.

[nasko, 2016/11/09 01:13:07]

They all send through the same IPC channel. What matters at the end is having
the correct routing ID.

[EhsanK, 2016/11/15 19:54:22]

Acknowledged.

+      new GuestViewMsg_GuestAttached(element_instance_id_,
+                                     guest_proxy_routing_id));
 
   SendQueuedEvents();
 }