[Chromoting] Add ability to enable/disable GDrive support per-app in gyp.

remoting/webapp/base/js/app_capabilities.js

Index: remoting/webapp/base/js/app_capabilities.js
diff --git a/remoting/webapp/base/js/app_capabilities.js b/remoting/webapp/base/js/app_capabilities.js
new file mode 100644
index 0000000000000000000000000000000000000000..655e9133c29014e2798aaf42a7e85cdf32e15073
--- /dev/null
+++ b/remoting/webapp/base/js/app_capabilities.js
@@ -0,0 +1,18 @@
+// 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.
+
+'use strict';
+
+/** @suppress {duplicate} */
+var remoting = remoting || {};
+
+/**
+ * Note that this needs to be a function because it gets expanded at
+ * compile-time into remoting.ClientSession.Capability enums and these
+ * are not guaranteed to be present yet when this file is loaded.
+ * @return {Array.<remoting.ClientSession.Capability>}
+ */
+remoting.app_capabilities = function() {
+  return ['APPLICATION_CAPABILITIES'];
+}