Added support for enabling GCD, or not, at build time.

remoting/webapp/crd/manifest.json.jinja2

 {
   {{ MANIFEST_KEY_FOR_UNOFFICIAL_BUILD }}
   "name": "__MSG_PRODUCT_NAME__",
   "version": "{{ FULL_APP_VERSION }}",
   "description": "__MSG_PRODUCT_DESCRIPTION__",
   "manifest_version": 2,
   "default_locale": "en",
   "minimum_chrome_version": "32",
   "app": {
 {% if webapp_type == 'v1' %}
@@ skipping 35 matching lines @@
   "content_security_policy": "default-src 'self'; script-src 'self' {{ TALK_GADGET_HOST }} https://www.gstatic.com; style-src 'self' https://fonts.googleapis.com; img-src 'self' {{ TALK_GADGET_HOST }} data:; font-src *; connect-src 'self' {{ OAUTH2_ACCOUNTS_HOST }} {{ GOOGLE_API_HOSTS }} {{ TALK_GADGET_HOST }} https://relay.google.com",
 {% endif %}
   "optional_permissions": [
     "<all_urls>"
   ],
 
 {% if webapp_type != 'v1' %}
   "oauth2": {
     "client_id": "{{ REMOTING_IDENTITY_API_CLIENT_ID }}",
     "scopes": [
-      "https://www.googleapis.com/auth/chromoting https://www.googleapis.com/auth/googletalk https://www.googleapis.com/auth/userinfo#email"
+      {% if USE_GCD %}
+      "https://www.googleapis.com/auth/clouddevices",
+      {% endif %}
+      "https://www.googleapis.com/auth/chromoting",
+      "https://www.googleapis.com/auth/googletalk",
+      "https://www.googleapis.com/auth/userinfo#email"
     ]
   },
   "sandbox": {
     "pages": [ "wcs_sandbox.html" ]
   },
 {% endif %}
   "permissions": [
     "{{ OAUTH2_ACCOUNTS_HOST }}/*",
     "{{ OAUTH2_API_BASE_URL }}/*",
     "{{ DIRECTORY_API_BASE_URL }}/*",
@@ skipping 24 matching lines @@
 {% endif %}
   ]
 {% if webapp_type != 'v1' %}
   ,"sockets": {
     "tcp": {
       "connect": "{{ XMPP_SERVER }}"
     }
   }
 {% endif %}
 }