Add ability APIs for opening a window with a url embedded, focusing and activating a window.

mojo/services/public/interfaces/window_manager/window_manager.mojom

 // 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.
 
 module mojo {
 
 [Client=WindowManagerClient]
 interface WindowManagerService {
   OpenWindow() => (uint32 node_id);
+  OpenWindowWithURL(string url) => (uint32 node_id);
   SetCapture(uint32 node_id) => (bool success);
+  FocusWindow(uint32 node_id) => (bool success);
+  ActivateWindow(uint32 node_id) => (bool success);
 };
 
 [Client=WindowManagerService]
 interface WindowManagerClient {
   // Called when the window manager is ready to use (in the event a client
   // connects to it before it has been initialized).
   OnWindowManagerReady();
 
   // TODO(beng): how is the WM supposed to know if a node is known to a client
   //             or not?
   OnCaptureChanged(uint32 old_capture_node_id, uint32 new_capture_node_id);
+
+  OnFocusChanged(uint32 old_focused_node_id, uint32 new_focused_node_id);
+  OnActiveWindowChanged(uint32 old_focused_window, uint32 new_focused_window);
 };
 
 }