Webapp changes to support third party authentication

remoting/webapp/manifest.json

 {
   "name": "__MSG_PRODUCT_NAME__",
   "version": "FULL_APP_VERSION",
   "description": "__MSG_PRODUCT_DESCRIPTION__",
   "manifest_version": 2,
   "default_locale": "en",
   "app": {
     "launch": {
       "local_path": "main.html"
     }
   },
   "icons": {
     "128": "chromoting128.webp",
     "48": "chromoting48.webp",
     "16": "chromoting16.webp"
   },
   "content_scripts": [
     {
       "matches": [
         "OAUTH2_REDIRECT_URL"
       ],
       "js": [ "cs_oauth2_trampoline.js" ]
+    },
+    {
+      "matches": [
+        "THIRD_PARTY_AUTH_REDIRECT_URL"
+      ],
+      "js": [ "cs_third_party_auth_trampoline.js" ]
     }
   ],
   "content_security_policy": "default-src 'self'; script-src 'self' TALK_GADGET_HOST; style-src 'self' https://fonts.googleapis.com; img-src 'self' TALK_GADGET_HOST; font-src *; connect-src 'self' OAUTH2_ACCOUNTS_HOST GOOGLE_API_HOSTS TALK_GADGET_HOST https://relay.google.com",
+  "optional_permissions": [
+    "<all_urls>"
+  ],
   "permissions": [
     "OAUTH2_ACCOUNTS_HOST/*",
     "OAUTH2_API_BASE_URL/*",
     "DIRECTORY_API_BASE_URL/*",
     "TALK_GADGET_HOST/talkgadget/*",
     "https://relay.google.com/*",
     "storage",
     "clipboardRead",
-    "clipboardWrite"
+    "clipboardWrite",
   ],
   "plugins": [
     { "path": "remoting_host_plugin.dll", "public": false },
     { "path": "libremoting_host_plugin.ia32.so", "public": false },
     { "path": "libremoting_host_plugin.x64.so", "public": false },
     { "path": "remoting_host_plugin.plugin", "public": false }
   ],
   "requirements": {
     "plugins": {
       "npapi": false
     }
   }
 }