Add new certificateProvider 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.
 
 // This features file defines permissions for 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.
 
 // To add a new whitelisted ID, SHA-1 it and force it to uppercase. In Bash:
@@ skipping 107 matching lines @@
     "whitelist": [
       "63ED55E43214C211F82122ED56407FF1A807F2A3",  // Dev
       "FA01E0B81978950F2BC5A50512FD769725F57510",  // Beta
       "B11A93E7E5B541F8010245EBDE2C74647D6C14B9",  // Canary
       "F155646B5D1CA545F7E1E4E20D573DFDD44C2540",  // Google Cast Beta
       "16CA7A47AAE4BE49B1E75A6B960C3875E945B264",  // Google Cast Stable
       "C17CD9E6868D7B9C67926E0EC612EA25C768418F",  // http://crbug.com/457908
       "EF2AB692559EA97C3BBDEA018A8C45F92457BD4E"   // http://crbug.com/457908
     ]
   }],
+  "certificateProvider": {
+    "channel": "stable",
+    "platforms": ["chromeos"],
+    "extension_types": ["extension", "platform_app"]
+  },
   "chromePrivate": {
     "channel": "stable",
     "extension_types": ["extension", "legacy_packaged_app"],
     "whitelist": [
       "2462D64ACB971A7E708757159C2B17761D4FF54A",  // Citrix Receiver
       "3010EF507AFEF487EEA9CDE2930EC94867C60936",  // Citrix Receiver Beta
       "ABAABC5F49E022A76CBB12972A53B58354C04AC6"   // Citrix Receiver Dev
     ]
   },
   "chromeosInfoPrivate": {
@@ skipping 908 matching lines @@
     "channel": "stable",
     "extension_types": ["platform_app"],
     "platforms": ["chromeos"],
     "whitelist": [
       "A948368FC53BE437A55FEB414106E207925482F5",  // Files app
       "8C726564C6DBE7380BAB388DE6CC7EC93EB44B06",  // Video player
       "5065C83E84321221675D20FBE4DC43C655CC8C6F"   // Files app tests
     ]
   }
 }