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

chrome/browser/background/background_contents_service.cc

 // 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.
 
 #include "chrome/browser/background/background_contents_service.h"
 
 #include "apps/app_load_service.h"
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 54 matching lines @@
 
 namespace {
 
 const char kNotificationPrefix[] = "app.background.crashed.";
 
 void CloseBalloon(const std::string& balloon_id) {
   NotificationUIManager* notification_ui_manager =
       g_browser_process->notification_ui_manager();
   bool cancelled ALLOW_UNUSED = notification_ui_manager->CancelById(balloon_id);
 #if defined(ENABLE_NOTIFICATIONS)
-  if (cancelled && message_center::IsRichNotificationEnabled()) {
+  if (cancelled) {
     // TODO(dewittj): Add this functionality to the notification UI manager's
     // API.
     g_browser_process->message_center()->SetVisibility(
         message_center::VISIBILITY_TRANSIENT);
   }
 #endif
 }
 
 // Closes the crash notification balloon for the app/extension with this id.
 void ScheduleCloseBalloon(const std::string& extension_id) {
@@ skipping 700 matching lines @@
     bool user_gesture,
     bool* was_blocked) {
   Browser* browser = chrome::FindLastActiveWithProfile(
       Profile::FromBrowserContext(new_contents->GetBrowserContext()),
       chrome::GetActiveDesktop());
   if (browser) {
     chrome::AddWebContents(browser, NULL, new_contents, disposition,
                            initial_pos, user_gesture, was_blocked);
   }
 }