Update the extension whitelist for application host change.

BUG=

Committed: https://crrev.com/29b6f6fa8785ed80c2fcf043bb0619f3f8b80065
Cr-Commit-Position: refs/heads/master@{#326534}

Review URL: https://codereview.chromium.org/1098403002

Cr-Commit-Position: refs/heads/master@{#326682}

chrome/browser/resources/hangout_services/manifest.json

@@ -7,7 +7,10 @@
   "manifest_version": 2,
   "externally_connectable": {
     "matches": [
-      "https://*.google.com/hangouts*",
+      "https://hangouts.google.com/*",
+      "https://talkgadget.google.com/*",
+      "https://*.talkgadget.google.com/*",
+      "https://plus.google.com/hangouts*",
       // For tests.
       "*://localhost/*"
     ]