Correctly find root RWHV from a nested WebContents

content/browser/frame_host/cross_process_frame_connector.cc

 // Copyright 2014 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.
 
 #include "content/browser/frame_host/cross_process_frame_connector.h"
 
 #include "cc/surfaces/surface.h"
 #include "cc/surfaces/surface_manager.h"
 #include "content/browser/compositor/surface_utils.h"
 #include "content/browser/frame_host/frame_tree.h"
@@ skipping 209 matching lines @@
 }
 
 void CrossProcessFrameConnector::SetSize(gfx::Rect frame_rect) {
   child_frame_rect_ = frame_rect;
   if (view_)
     view_->SetSize(frame_rect.size());
 }
 
 RenderWidgetHostViewBase*
 CrossProcessFrameConnector::GetRootRenderWidgetHostView() {
-  return static_cast<RenderWidgetHostViewBase*>(
-      frame_proxy_in_parent_renderer_->frame_tree_node()
-          ->frame_tree()
-          ->root()
-          ->current_frame_host()
-          ->GetView());
+  RenderFrameHostImpl* top_host = frame_proxy_in_parent_renderer_->
+      frame_tree_node()->frame_tree()->root()->current_frame_host();
+
+  // This method should return the root RWHV from the top-level WebContents,
+  // in the case of nested WebContents.
+  if (top_host->frame_tree_node()->render_manager()->ForInnerDelegate()) {

[nasko, 2015/10/30 21:29:12]

This will just go one level up, right? I'm not sure if we have currently an easy
way to get to multiple levels of nesting in real code, but I think we should
structure the code to handle that. I think just changing the if into a while
should do the trick, right?

[kenrb, 2015/10/30 21:40:40]

I guess it might be more intuitive to do this. Originally I had thought it would
just jump to the next level up, and then call the appropriate method on that
RenderWidgetHostView, which could proxy again if it happened to be a
doubly-nested WebContents (this is how the bug caused infinite recursion). Since
we don't support more than one layer of WebContents anyway this is hypothetical,
but you're right it is easy to make it return the final target.

+    top_host = top_host->frame_tree_node()->render_manager()->
+        GetOuterDelegateNode()->frame_tree()->root()->current_frame_host();
+  }
+
+  return static_cast<RenderWidgetHostViewBase*>(top_host->GetView());
 }
 
 }  // namespace content