Track permissions granted to extensions in prefs

chrome/test/data/extensions/permissions/Preferences-unknown-api

+{
+   "extensions": {
+      "settings": {
+         "bcflfiohkjolmhmjjocpfbloomonhpkc": {
+            "app_launcher_index": 13,
+            "granted_permissions": {
+              "initialized": true,
+              "host": [ "http://*.google.com/*", "https://*.google.com/*" ]
+            },
+            "incognito": false,
+            "location": 1,
+            "path": "bcflfiohkjolmhmjjocpfbloomonhpkc/1_0",
+            "state": 1,
+            "manifest": {
+               "content_scripts": [ {
+                    "js": [ "test.js" ],
+                    "matches": [ "http://*.google.com/*", "https://*.google.com/*" ]
+               } ],
+               "key": "MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQCjaeNnkVsxxIdwFiIWDDaiCUGLAxpl8zuMn6za/zFOw4ManeaA7o0NkEnpgtBcVT40zU48H/invljVB6TDaQ93RSnD3P6esUgJTqlJg7vz9zlUsefTBmLChPR38zW87l8TIIEvt3Syb5iFf35KUXdUujiCtO2Pb3Adh1cuDUXo8QIDAQAB",
+               "name": "Unknown Permissions Test",
+               "permissions": [ "tabs", "blah" ],
+               "version": "1"
+            }
+         }
+      }
+   }
+}