arc-bridge: Enable ARC with a command-line flag

chrome/browser/ui/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/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 
 gypi_values = exec_script("//build/gypi_to_gn.py",
                           [ rebase_path("../../chrome_browser_ui.gypi") ],
@@ skipping 179 matching lines @@
     sources +=
         rebase_path(gypi_values.chrome_browser_ui_chromeos_non_official_sources,
                     ".",
                     "//chrome")
   }
 
   if (is_chromeos) {
     sources += rebase_path(gypi_values.chrome_browser_ui_chromeos_sources,
                            ".",
                            "//chrome")
-    deps += [ "//chrome/browser/chromeos" ]
+    deps += [
+      "//chrome/browser/chromeos",
+      "//components/arc",
+    ]
   } else {
     defines += [ "FRAME_AVATAR_BUTTON=1" ]
   }
-  if (is_chromeos && enable_arc) {
-    deps += [ "//components/arc" ]
-  }
   if (use_cups) {
     configs += [ "//printing:cups" ]
   }
   if (use_ash) {
     sources +=
         rebase_path(gypi_values.chrome_browser_ui_ash_sources, ".", "//chrome")
     deps += [
       "//ash",
       "//ash:ash_with_content",
       "//ash/strings",
@@ skipping 385 matching lines @@
     "//chrome/browser",
     "//content/public/browser",
     "//content/public/common",
     "//content/test:test_support",
     "//net:test_support",
     "//skia",
     "//testing/gtest",
     "//ui/base",
   ]
 }