Turned UiStrings into a singleton so that the continue window does not depend on ChromotingHost.

remoting/host/disconnect_window.h

Index: remoting/host/disconnect_window.h
diff --git a/remoting/host/disconnect_window.h b/remoting/host/disconnect_window.h
index 1bc053bba099046c19e6cb7944f93fd4cb59a945..7c38bfa796c39a2097badeacaed593491c96a929 100644
--- a/remoting/host/disconnect_window.h
+++ b/remoting/host/disconnect_window.h
@@ -23,20 +23,20 @@ class DisconnectWindow {
   virtual ~DisconnectWindow() {}
 
   // Shows the disconnect window, allowing the user to disconnect the session.
-  // The window will display text from |ui_strings| and |username|.
   // |disconnect_callback| will be invoked on the calling UI thread when the
   // user chooses to disconnect, or if the window is closed by any means other
   // than Hide(), or deletion of the DisconnectWindow instance.
   // Show returns false if the window cannot be shown, in which case the
   // callback will not be invoked.
-  virtual bool Show(const UiStrings& ui_strings,
-                    const base::Closure& disconnect_callback,
+  virtual bool Show(const base::Closure& disconnect_callback,
                     const std::string& username) = 0;
 
   // Hides the disconnect window. The disconnect callback will not be invoked.
   virtual void Hide() = 0;
 
-  static scoped_ptr<DisconnectWindow> Create();
+  // |ui_strings| specifies localized strings to be used by the window.
+  // |ui_strings| must outlive the returned object.
+  static scoped_ptr<DisconnectWindow> Create(const UiStrings* ui_strings);
 };
 
 }  // namespace remoting