SendPageMessage() should not send to a WebView guest's embedder.

content/browser/frame_host/render_frame_host_manager.cc

Index: content/browser/frame_host/render_frame_host_manager.cc
diff --git a/content/browser/frame_host/render_frame_host_manager.cc b/content/browser/frame_host/render_frame_host_manager.cc
index 58c17d54c34798e0e070878e4e572a594f41a3a3..f8472e4093d6195a97ad97830d07bb4143d48816 100644
--- a/content/browser/frame_host/render_frame_host_manager.cc
+++ b/content/browser/frame_host/render_frame_host_manager.cc
@@ -2503,8 +2503,13 @@ void RenderFrameHostManager::SendPageMessage(IPC::Message* msg) {
     sender->Send(copy);
   };
 
-  for (const auto& pair : proxy_hosts_)
-    send_msg(pair.second.get(), pair.second->GetRoutingID(), msg);
+  // When sending a PageMessage to a WebView's guest, we don't want to also

[nasko, 2016/05/04 21:58:59]

nit: WebView is overloaded term, let's avoid using it, especially in content/,
which doesn't even have that concept. We have the inner/outer relationship we
can use here.

[wjmaclean, 2016/05/05 15:40:56]

Done.

+  // send it to the embedder's frames as well. A WebView guest frame tree should
+  // have no proxies other than for its embedder.
+  if (!ForInnerDelegate()) {

[nasko, 2016/05/04 21:58:59]

This will not be true if we allow cross-process navigations in GuestViews. Can
we instead compare the SiteInstance of the proxy with the SiteInstance of the
outer WebContents node?

[wjmaclean, 2016/05/05 15:40:56]

I'm not sure I understand this. What if some sub-frame to the inner contents has
the same SiteInstance as the outer WebContents? How would we differentiate them?

+    for (const auto& pair : proxy_hosts_)
+      send_msg(pair.second.get(), pair.second->GetRoutingID(), msg);
+  }
 
   if (speculative_render_frame_host_) {
     send_msg(speculative_render_frame_host_.get(),