Service CreateNewWindow on the UI thread with a new mojo interface

content/browser/frame_host/render_frame_host_delegate.h

Index: content/browser/frame_host/render_frame_host_delegate.h
diff --git a/content/browser/frame_host/render_frame_host_delegate.h b/content/browser/frame_host/render_frame_host_delegate.h
index 197b64b49fd6bf0efbbd6f5a2ba705a7700fc580..524e4c2cf3f1b2923fd13087fdad4ee045dcb85e 100644
--- a/content/browser/frame_host/render_frame_host_delegate.h
+++ b/content/browser/frame_host/render_frame_host_delegate.h
@@ -252,6 +252,8 @@ class CONTENT_EXPORT RenderFrameHostDelegate {
   // container that is requested -- in particular, the window.open call may have
   // specified 'background' and 'persistent' in the feature string.
   //
+  // The passed |opener| is the RenderFrameHost initiating the window creation.
+  //
   // The passed |params.frame_name| parameter is the name parameter that was
   // passed to window.open(), and will be empty if none was passed.
   //
@@ -264,6 +266,7 @@ class CONTENT_EXPORT RenderFrameHostDelegate {
   // returns.
   virtual void CreateNewWindow(
       SiteInstance* source_site_instance,
+      RenderFrameHost* opener,
       int32_t render_view_route_id,
       int32_t main_frame_route_id,
       int32_t main_frame_widget_route_id,