[Extensions] Move Feature channel code into //extensions

extensions/common/features/complex_feature.cc

 // 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.
 
 #include "extensions/common/features/complex_feature.h"
 
 namespace extensions {
 
 ComplexFeature::ComplexFeature(std::unique_ptr<FeatureList> features) {
   DCHECK_GT(features->size(), 0UL);
@@ skipping 84 matching lines @@
   }
   return false;
 }
 
 bool ComplexFeature::IsInternal() const {
   // Constructor verifies that composed features are consistent, thus we can
   // return just the first feature's value.
   return features_[0]->IsInternal();
 }
 
-std::string ComplexFeature::GetAvailabilityMessage(AvailabilityResult result,

[Devlin, 2016/07/08 21:20:21]

Strangely, the only time this is actually called is by line 114 (in this
method), so I believe this was unused.

[lazyboy, 2016/07/12 00:35:12]

Acknowledged.

-                                                   Manifest::Type type,
-                                                   const GURL& url,
-                                                   Context context) const {
-  if (result == IS_AVAILABLE)
-    return std::string();
-
-  // TODO(justinlin): Form some kind of combined availabilities/messages from
-  // SimpleFeatures.
-  return features_[0]->GetAvailabilityMessage(result, type, url, context);
-}
-
 }  // namespace extensions