Make the chrome.usb API available to Extensions.

extensions/common/api/_permission_features.json

 // Copyright 2014 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 permissions for extension APIs implemented
 // under src/extensions.
 
 // See extensions/common/features/* to understand this file, in particular
 // feature.h, simple_feature.h, and base_feature_provider.h.
 
@@ skipping 351 matching lines @@
         "C06709A259378015404ED20F75C7D08547E0F10B"   // Security Key (dev)
       ]
     }
   ],
   "unlimitedStorage": {
     "channel": "stable",
     "extension_types": [
       "extension", "legacy_packaged_app", "hosted_app", "platform_app"
     ]
   },
-  "usb": [
-    {
-      "channel": "stable",
-      "extension_types": ["platform_app"]
-    },
-    {
-      "channel": "stable",
-      "extension_types": ["extension"],
-      "whitelist": [
-        "496B6890097EB6E19809ADEADD095A8721FBB2E0",  // FIDO U2F APIs
-        "AD8ED80B705E1818AAD4684F9FF62B43D6D79620",  // FIDO U2F APIs (dev)
-        "E24F1786D842E91E74C27929B0B3715A4689A473",  // CryptoToken
-        "A28C9619C4C41306FA5236FB4D94DA812F504DE8"   // CryptoToken (dev)
-      ]
-    }
-  ],
-  "usbDevices": [
-    {
-      "channel": "stable",
-      "extension_types": ["platform_app"]
-    },
-    {
-      "channel": "stable",
-      "extension_types": ["extension"],
-      "whitelist": [
-        "496B6890097EB6E19809ADEADD095A8721FBB2E0",  // FIDO U2F APIs
-        "AD8ED80B705E1818AAD4684F9FF62B43D6D79620",  // FIDO U2F APIs (dev)
-        "E24F1786D842E91E74C27929B0B3715A4689A473",  // CryptoToken
-        "A28C9619C4C41306FA5236FB4D94DA812F504DE8"   // CryptoToken (dev)
-      ]
-    }
-  ],
+  "usb": {
+    "channel": "stable",
+    "extension_types": ["extension", "platform_app"]
+  },
+  "usbDevices": {
+    "channel": "stable",
+    "extension_types": ["extension", "platform_app"]
+  },
   "videoCapture": [
     {
       "channel": "stable",
       "extension_types": ["platform_app"]
     },
     {
       "channel": "stable",
       "extension_types": ["extension"],
       "whitelist": [
         // http://crbug.com/292856
@@ skipping 25 matching lines @@
   },
   "webRequest": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
    },
   "webRequestBlocking": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"]
   }
 }