Add chrome/browser/apps/BUILD.gn and move Chrome-specific code there

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 <utility>
 
-#include "apps/app_load_service.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
 #include "base/location.h"
 #include "base/macros.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/single_thread_task_runner.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/time.h"
 #include "base/values.h"
+#include "chrome/browser/apps/app_load_service.h"
 #include "chrome/browser/background/background_contents_service_factory.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chrome_notification_types.h"
 #include "chrome/browser/extensions/extension_service.h"
 #include "chrome/browser/notifications/notification.h"
 #include "chrome/browser/notifications/notification_delegate.h"
 #include "chrome/browser/notifications/notification_ui_manager.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/browser.h"
@@ skipping 816 matching lines @@
     const gfx::Rect& initial_rect,
     bool user_gesture,
     bool* was_blocked) {
   Browser* browser = chrome::FindLastActiveWithProfile(
       Profile::FromBrowserContext(new_contents->GetBrowserContext()));
   if (browser) {
     chrome::AddWebContents(browser, NULL, new_contents, disposition,
                            initial_rect, user_gesture, was_blocked);
   }
 }