Disable extension Panels on Dev and Canary, except for the whitelist

chrome/common/extensions/api/_api_features.json

 // Copyright (c) 2012 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.
 
 // This features file defines extension APIs implemented under src/chrome.
 // See extensions/common/features/* to understand this file, in particular
 // feature.h, simple_feature.h, and base_feature_provider.h.
 //
 // Note that specifying "web_page", "blessed_web_page", or "all" as a context
 // type will require manually updating chrome/renderer/resources/dispatcher.cc.
@@ skipping 464 matching lines @@
     "contexts": ["blessed_extension"]
   },
   "gcm": {
     "dependencies": ["permission:gcm"],
     "contexts": ["blessed_extension"]
   },
   "hangoutsPrivate": {
     "channel": "stable",
     "contexts": ["blessed_extension"],
     "whitelist": [
-      // http://crbug.com/309737
-      "nckgahadagoaajjgafhacjanaoiihapd",
-      "ljclpkphhpbpinifbeabbhlfddcpfdde",
-      "ppleadejekpmccmnpjdimmlfljlkdfej",
-      "eggnbpckecmjlblplehfpjjdhhidfdoj",
-      "jfjjdfefebklmdbmenmlehlopoocnoeh",
-      "knipolnnllmklapflnccelgolnpehhpl"
+      // http://crbug.com/309737.
+      // Keep this list in sync with extensions_misc::kHangoutsExtensionIds.
+      "nckgahadagoaajjgafhacjanaoiihapd",  // Hangouts Production.
+      "ljclpkphhpbpinifbeabbhlfddcpfdde",  // Hangouts Debug.
+      "ppleadejekpmccmnpjdimmlfljlkdfej",  // Hangouts Alpha.
+      "eggnbpckecmjlblplehfpjjdhhidfdoj",  // Hangouts Beta.
+      "jfjjdfefebklmdbmenmlehlopoocnoeh",  // Hangouts Packaged App Debug.
+      "knipolnnllmklapflnccelgolnpehhpl"   // Hangouts Packaged App Prod.
     ]
   },
   "history": {
     "dependencies": ["permission:history"],
     "contexts": ["blessed_extension"]
   },
   "hotwordPrivate": {
     "dependencies": ["permission:hotwordPrivate"],
     "contexts": ["blessed_extension"]
   },
@@ skipping 323 matching lines @@
     "internal": true,
     "channel": "stable",
     "dependencies": ["permission:webview"],
     "contexts": ["blessed_extension"]
   },
   "windows": {
     "dependencies": ["api:tabs"],
     "contexts": ["blessed_extension"]
   }
 }