Allow MimeHandlerViewGuest be embedded inside OOPIFs

content/public/browser/browser_plugin_guest_delegate.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_PUBLIC_BROWSER_BROWSER_PLUGIN_GUEST_DELEGATE_H_
 #define CONTENT_PUBLIC_BROWSER_BROWSER_PLUGIN_GUEST_DELEGATE_H_
 
 #include "base/callback_forward.h"
 #include "base/process/kill.h"
 #include "content/common/content_export.h"
@@ skipping 75 matching lines @@
   // Sets the position of the context menu for the guest contents. The value
   // reported from the guest renderer should be ignored. The reported value
   // fromt he guest renderer is incorrect in situations where BrowserPlugin is
   // subject to CSS transforms.
   virtual void SetContextMenuPosition(const gfx::Point& position) {}
 
   // TODO(ekaramad): A short workaround to force some types of guests to use
   // a BrowserPlugin even when we are using cross process frames for guests. It
   // should be removed after resolving https://crbug.com/642826).
   virtual bool CanUseCrossProcessFrames();
+
+  // Returns the RenderFrameHost corresponding to the RenderFrame embedding the
+  // BrowserPlugin. This is the main frame for the owner of the guests, unless
+  // the guest is embedded inside a cross origin frame.

[Charlie Reis, 2016/11/15 23:45:33]

Sorry, I don't think this API makes sense.  The first sentence is incorrect if
the BrowserPlugin is inside a same-origin iframe rather than the main frame.

It may happen to work out because the current callers only care about
widget-level concepts (RWHV, process, SiteInstance), but it will break any
future code that assumes it returns the actual embedding frame.

Would returning the owner RenderWidgetHost or RenderWidgetHostView work instead?
 Maybe with a separate GetOwnerSiteInstance since RenderWidgetHost doesn't know
its SiteInstance?

[EhsanK, 2016/11/16 21:27:31]

Yes you are right. I was too focused on the OOPIF case when adding this comment.
Agreed. Basically, the whole guest->embedder communication is through the
RenderWidgetHost.
Done.

+  virtual RenderFrameHost* GetOwnerFrame();
+
+  // Returns true if the corresponding guest is allowed to be embedded inside an
+  // <iframe> which is cross process.
+  virtual bool CanBeEmbeddedInsideCrossProcessFrames();
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_BROWSER_PLUGIN_GUEST_DELEGATE_H_