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

chrome/browser/BUILD.gn

 # Copyright 2014 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.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
 import("//chrome/common/features.gni")
@@ skipping 1906 matching lines @@
       "sync_file_system/syncable_file_system_util.h",
       "sync_file_system/task_logger.cc",
       "sync_file_system/task_logger.h",
     ]
     if (enable_media_router) {
       sources += [
         "media/cast_transport_host_filter.cc",
         "media/cast_transport_host_filter.h",
       ]
     }
-    public_deps += [ "//chrome/browser/extensions" ]
-    allow_circular_includes_from += [ "//chrome/browser/extensions" ]
+    public_deps += [
+      "//chrome/browser/apps",
+      "//chrome/browser/extensions",
+    ]
+    allow_circular_includes_from += [
+      "//chrome/browser/apps",
+      "//chrome/browser/extensions",
+    ]
     deps += [
       "//chrome/browser/sync_file_system/drive_backend:sync_file_system_drive_proto",
       "//chrome/common/extensions/api",
       "//chrome/common/extensions/api:api_registration",
       "//chrome/common/extensions/api:extensions_features",
       "//components/drive",
       "//components/proximity_auth/ble",
       "//extensions/components/javascript_dialog_extensions_client",
       "//media/cast:net",
     ]
@@ skipping 2717 matching lines @@
       "media/pepper_cdm_test_constants.cc",
       "media/pepper_cdm_test_constants.h",
     ]
   }
 }
 
 service_manifest("preferences_forwarder_manifest") {
   name = "preferences_forwarder"
   source = "prefs/forwarder_manifest.json"
 }