[Blimp Engine] Adds a WindowTreeClient so that popup will have non-null paren…

blimp/engine/session/blimp_engine_session.h

 // Copyright 2015 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.
 
 #ifndef BLIMP_ENGINE_SESSION_BLIMP_ENGINE_SESSION_H_
 #define BLIMP_ENGINE_SESSION_BLIMP_ENGINE_SESSION_H_
 
 #include <stdint.h>
 
 #include <vector>
@@ skipping 164 matching lines @@
   // be rendered.
   scoped_ptr<BlimpWindowTreeHost> window_tree_host_;
 
   // Used to apply standard focus conventions to the windows in the
   // WindowTreeHost hierarchy.
   scoped_ptr<wm::FocusController> focus_client_;
 
   // Used to manage input capture.
   scoped_ptr<aura::client::DefaultCaptureClient> capture_client_;
 
+  // Used to locate null-parented windows, such as a popup.

[Wez, 2016/03/29 21:20:06]

"locate" is ambiguous; I think you mean "locate in the window hierarchy"?

Suggest: "Used to attach null-parented windows (e.g. popups) to the root
window."

[haibinlu, 2016/03/29 21:57:16]

Done.

+  scoped_ptr<aura::client::WindowTreeClient> window_tree_client_;
+
   // Only one web_contents is supported for blimp 0.5
   scoped_ptr<content::WebContents> web_contents_;
 
   // Handles all incoming and outgoing messages related to RenderWidget,
   // including INPUT, COMPOSITOR and RENDER_WIDGET messages.
   EngineRenderWidgetFeature render_widget_feature_;
 
   // Container for connection manager, authentication handler, and
   // browser connection handler. The components run on the I/O thread, and
   // this object is destroyed there.
   scoped_ptr<EngineNetworkComponents> net_components_;
 
   scoped_ptr<ThreadPipeManager> thread_pipe_manager_;
 
   // Used to send TAB_CONTROL or NAVIGATION messages to client.
   scoped_ptr<BlimpMessageProcessor> tab_control_message_sender_;
   scoped_ptr<BlimpMessageProcessor> navigation_message_sender_;
 
   DISALLOW_COPY_AND_ASSIGN(BlimpEngineSession);
 };
 
 }  // namespace engine
 }  // namespace blimp
 
 #endif  // BLIMP_ENGINE_SESSION_BLIMP_ENGINE_SESSION_H_