Add WebRTC logging extension API.

chrome/common/extensions/api/_permission_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.
 
 // See c/c/e/features/* to understand this file, in particular feature.h,
 // simple_feature.h, and base_feature_provider.h.
 
 {
   "activeTab": {
     "channel": "stable",
@@ skipping 654 matching lines @@
   },
   "wallpaperPrivate": {
     "channel": "stable",
     "extension_types": ["platform_app"],
     "location": "component"
   },
   "webNavigation": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
   },
+  "webrtcLoggingPrivate": [{
+    "channel": "dev",
+    "extension_types": ["extension"],
+    "whitelist": ["80B9DC58E5210749F052F5B4DB239C50CF72AEB6"]
+  },{
+    "channel": "beta",
+    "extension_types": ["extension"],
+    "whitelist": ["80B9DC58E5210749F052F5B4DB239C50CF72AEB6"]
+  },{
+    "channel": "stable",
+    "extension_types": ["extension"],
+    "whitelist": ["80B9DC58E5210749F052F5B4DB239C50CF72AEB6"]
+  }],

[Finnur, 2013/09/04 13:45:56]

I don't think this is correct. There should only be one entry and the 'channel'
specifies how far it should go. 'dev' is appropriate for now. When we are ready
we can change it to 'beta' and then eventually to 'stable'.

[Henrik Grunell, 2013/09/04 13:53:09]

Ah OK. The other with several entries all have different setups I see now. Done.

   "webstorePrivate": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"],
     "whitelist": [
       "ahfgeienlihckogmohjhadlkjgocpleb",  // Web Store
       "afchcafgojfnemjkcbhfekplkmjaldaa"   // Enterprise Web Store
     ]
   },
   "webRequest": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
   },
   "webRequestBlocking": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
   },
   "webview": {
     "channel": "stable",
     "extension_types": ["platform_app"]
   }
 }