Service CreateNewWindow on the UI thread with a new mojo interface

content/common/render_message_filter.mojom

 // Copyright 2016 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.
 
 module content.mojom;
 
 import "cc/ipc/shared_bitmap_manager.mojom";
 import "content/common/native_types.mojom";
 import "content/public/common/window_container_type.mojom";
 import "gpu/ipc/common/mailbox.mojom";
@@ skipping 62 matching lines @@
   int32 main_frame_widget_route_id;
 
   // Duplicated from CreateNewWindowParams because legacy code.
   int64 cloned_session_storage_namespace_id;
 };
 
 interface RenderMessageFilter {
   // Synchronously generates a new routing ID for the caller.
   [Sync] GenerateRoutingID() => (int32 routing_id);
 
-  // Sent by the renderer when it is creating a new window.  The browser creates
-  // a tab for it.  If |reply.route_id| is MSG_ROUTING_NONE, the view couldn't
-  // be created.
-  [Sync] CreateNewWindow(CreateNewWindowParams params)
-      => (CreateNewWindowReply reply);
-
   // Similar to CreateWindow, except used for sub-widgets, like <select>
   // dropdowns.
   [Sync] CreateNewWidget(int32 opener_id, content.mojom.WebPopupType popup_type)
       => (int32 route_id);
 
   // Similar to CreateWidget except the widget is a full screen window.
   [Sync] CreateFullscreenWidget(int32 opener_id)
       => (int32 route_id);
 
   GetSharedBitmapManager(associated cc.mojom.SharedBitmapManager& bitmap_manager);
 };
+
+// Similar to RenderMessageFilter, but all IPCs are serviced on the UI thread.
+interface RenderMessageFilterUI {
+  // Sent by the renderer when it is creating a new window.  The browser creates
+  // a tab for it.  If |reply.route_id| is MSG_ROUTING_NONE, the view couldn't
+  // be created.
+  [Sync] CreateNewWindow(CreateNewWindowParams params)
+      => (CreateNewWindowReply reply);
+};