Implement BrowserList::AllBrowsersClosed for Linux.

chrome/chrome.gyp

 # Copyright (c) 2009 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.
 
 {
   'variables': {
     'chromium_code': 1,
 
     # Define the common dependencies that contain all the actual
     # Chromium functionality.  This list gets pulled in below by
@@ skipping 791 matching lines @@
         'browser/browser.cc',
         'browser/browser.h',
         'browser/browser_about_handler.cc',
         'browser/browser_about_handler.h',
         'browser/browser_accessibility.cc',
         'browser/browser_accessibility.h',
         'browser/browser_accessibility_manager.cc',
         'browser/browser_accessibility_manager.h',
         'browser/browser_init.cc',
         'browser/browser_init.h',
+        'browser/browser_list_gtk.cc',
         'browser/browser_list.cc',
         'browser/browser_list.h',
         'browser/browser_main.cc',
         'browser/browser_main_gtk.cc',
         'browser/browser_main_mac.mm',
         'browser/browser_main_win.cc',
         'browser/browser_main_win.h',
         'browser/browser_prefs.cc',
         'browser/browser_prefs.h',
         'browser/browser_process.cc',
@@ skipping 5843 matching lines @@
               'defines': [
                 'POSIX',
               ],
             }],
           ],
         },
       ],  # targets when chrome_personalization==1 and use_syncapi_stub==0
     }],
   ],  # 'conditions'
 }