Move enable_remoting build flag to remoting dir.

remoting/webapp/build_template.gni

 # Copyright 2015 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.
 
 # Keep in sync with 'remoting_webapp' target in remoting/remoting_client.gypi.
 
 import("//build/config/chrome_build.gni")
 import("//build/config/features.gni")
 import("//build/util/version.gni")
+import("//remoting/remoting_enable.gni")
 import("//remoting/remoting_locales.gni")
 import("//remoting/remoting_options.gni")
 import("//remoting/remoting_version.gni")
 import("//remoting/webapp/files.gni")
 import("//third_party/closure_compiler/closure_args.gni")
 
 # The base remoting directory that is used as the root directory for file
 # references. Many of the scripts rely on the files being specified relative
 # to this directory.
 remoting_dir = "//remoting"
@@ skipping 270 matching lines @@
     args += [
       "--locales_listfile",
       rebase_path(locales_listfile_output, root_build_dir),
     ]
     args += [
       "--use_gcd",
       "$remoting_use_gcd",
     ]
   }
 }