Enable content_capabilities on dev channel

extensions/common/api/_manifest_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 manifest keys implemented under src/extensions.
 // 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 68 matching lines @@
       "1C93BD3CF875F4A73C0B2A163BB8FBDA8B8B3D80",  // http://crbug.com/396117
       "A3BC37E2148AC4E99BE4B16AF9D42DD1E592BBBE",  // http://crbug.com/396117
       "E703483CEF33DEC18B4B6DD84B5C776FB9182BDB",  // http://crbug.com/396117
       "307E96539209F95A1A8740C713E6998A73657D96",  // http://crbug.com/396117
       "4F25792AF1AA7483936DE29C07806F203C7170A0",  // http://crbug.com/407693
       "BD8781D757D830FC2E85470A1B6E8A718B7EE0D9",  // http://crbug.com/407693
       "4AC2B6C63C6480D150DFDA13E4A5956EB1D0DDBB",  // http://crbug.com/407693
       "81986D4F846CEDDDB962643FA501D1780DD441BB"   // http://crbug.com/407693
     ]
   }],
-  "content_capabilities": {
+  "content_capabilities": [{
     "channel": "stable",
     "extension_types": ["extension"],
     "whitelist": [
       "950D13BB9B4794F4CA2A68D3597E5DFAA47C88AE"  // Drive
     ]
-  },
+  }, {
+    "channel": "dev",

[not at google - send to devlin, 2015/03/04 17:37:45]

You could also enable on canary only, if this is just for the purpose of
testing?

+    "extension_types": ["extension"]
+  }],
   "content_security_policy": {
     "channel": "stable",
     // Platform apps have a restricted content security policy that cannot be
     // overriden (except for a whitelist of exceptions, see the
     // app.content_security_policy whitelist).
     "extension_types": ["extension", "legacy_packaged_app"]
   },
   "copresence" : {
     "channel": "stable",
     "extension_types": "all"
@@ skipping 178 matching lines @@
       "extension_types": ["platform_app"],
       "location": "component"
     }
   ],
   "webview": {
     "channel": "stable",
     "extension_types": ["platform_app"],
     "min_manifest_version": 2
   }
 }