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

remoting/host/disconnect_window_mac.h

 // Copyright (c) 2012 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.
 
 #import <Cocoa/Cocoa.h>
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/string16.h"
 #include "base/utf_string_conversions.h"
 #include "remoting/host/disconnect_window.h"
 
 namespace remoting {
 struct UiStrings;
 }
 
 // Controller for the disconnect window which allows the host user to
 // quickly disconnect a session.
 @interface DisconnectWindowController : NSWindowController {
  @private
-  bool rtl_;
-  string16 disconnect_message_;
-  string16 disconnect_button_text_;
+  const remoting::UiStrings* ui_strings_;
   base::Closure disconnect_callback_;
   string16 username_;
   IBOutlet NSTextField* connectedToField_;
   IBOutlet NSButton* disconnectButton_;
 }
 
-- (id)initWithUiStrings:(const remoting::UiStrings&)ui_strings
+- (id)initWithUiStrings:(const remoting::UiStrings*)ui_strings
                callback:(const base::Closure&)disconnect_callback
                username:(const std::string&)username;
 - (IBAction)stopSharing:(id)sender;
 @end
 
 // A floating window with a custom border. The custom border and background
 // content is defined by DisconnectView. Declared here so that it can be
 // instantiated via a xib.
 @interface DisconnectWindow : NSWindow
 @end
 
 // The custom background/border for the DisconnectWindow. Declared here so that
 // it can be instantiated via a xib.
 @interface DisconnectView : NSView
 @end