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

chrome/browser/chrome_notification_types.h

 // Copyright 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_CHROME_NOTIFICATION_TYPES_H_
 #define CHROME_BROWSER_CHROME_NOTIFICATION_TYPES_H_
 
 #include "build/build_config.h"
 #include "content/public/browser/notification_types.h"
 
@@ skipping 572 matching lines @@
   // Sent when the extension updater starts checking for updates to installed
   // extensions. The source is a Profile, and there are no details.
   NOTIFICATION_EXTENSION_UPDATING_STARTED,
 
   // The extension updater found an update and will attempt to download and
   // install it. The source is a Profile, and the details are an
   // extensions::UpdateDetails object with the extension id and version of the
   // found update.
   NOTIFICATION_EXTENSION_UPDATE_FOUND,
 
-  // Desktop Notifications ---------------------------------------------------
-
-  // This notification is sent when a balloon is connected to a renderer
-  // process to render the balloon contents.  The source is a
-  // Source<BalloonHost> with a pointer to the the balloon.  A
-  // NOTIFY_BALLOON_DISCONNECTED is guaranteed before the source pointer
-  // becomes junk. No details expected.
-  NOTIFICATION_NOTIFY_BALLOON_CONNECTED,
-
-  // This message is sent after a balloon is disconnected from the renderer
-  // process. The source is a Source<BalloonHost> with a pointer to the
-  // balloon host (the pointer is usable). No details are expected.
-  NOTIFICATION_NOTIFY_BALLOON_DISCONNECTED,
-
   // Upgrade notifications ---------------------------------------------------
 
   // Sent when Chrome believes an update has been installed and available for
   // long enough with the user shutting down to let it take effect. See
   // upgrade_detector.cc for details on how long it waits. No details are
   // expected.
   NOTIFICATION_UPGRADE_RECOMMENDED,
 
   // Sent when a critical update has been installed. No details are expected.
   NOTIFICATION_CRITICAL_UPGRADE_INSTALLED,
@@ skipping 340 matching lines @@
   // Note:-
   // Currently only Content and Chrome define and use notifications.
   // Custom notifications not belonging to Content and Chrome should start
   // from here.
   NOTIFICATION_CHROME_END,
 };
 
 }  // namespace chrome
 
 #endif  // CHROME_BROWSER_CHROME_NOTIFICATION_TYPES_H_