Add a Record button to the web-app if the host supports video recording.

remoting/webapp/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 49 matching lines @@
     "{{ OAUTH2_API_BASE_URL }}/*",
     "{{ DIRECTORY_API_BASE_URL }}/*",
     "{{ TALK_GADGET_HOST }}/talkgadget/*",
     "https://relay.google.com/*",
     "storage",
     "clipboardRead",
     "clipboardWrite",
     "nativeMessaging"
 {% if webapp_type != 'v1' %}
     ,
+    {"fileSystem": ["write"]},
     "fullscreen",
     "identity",
     "contextMenus",
     "overrideEscFullscreen"
 {% endif %}
 {% if webapp_type == 'v2_pnacl' %}
     ,{
       "socket": [
         "tcp-connect",
         "tcp-listen",
         "udp-send-to",
         "udp-bind",
         "udp-multicast-membership",
         "resolve-host",
         "network-state"
       ]
     }
 {% endif %}
   ]
 }