Remove balloon notification code. The last user was the Linux GTK port but that's deleted now.

chrome/browser/notifications/notification_ui_manager.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.
 
 #ifndef CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_UI_MANAGER_H_
 #define CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_UI_MANAGER_H_
 
 #include <set>
 #include <string>
 #include <vector>
@@ skipping 40 matching lines @@
   // extension ID). Returns true if anything was removed.
   virtual bool CancelAllBySourceOrigin(const GURL& source_origin) = 0;
 
   // Removes notifications matching |profile|. Returns true if any were removed.
   virtual bool CancelAllByProfile(Profile* profile) = 0;
 
   // Cancels all pending notifications and closes anything currently showing.
   // Used when the app is terminating.
   virtual void CancelAll() = 0;
 
-  // Temporary, while we have two implementations of Notifications UI Managers.
-  // One is older BalloonCollection-based and uses renderers to show
-  // notifications, another delegates to the new MessageCenter and uses native
-  // UI widgets.
-  // TODO(dimich): remove these eventually.
-  static bool DelegatesToMessageCenter();
-
  protected:
   NotificationUIManager() {}
 
  private:
   DISALLOW_COPY_AND_ASSIGN(NotificationUIManager);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_NOTIFICATION_UI_MANAGER_H_