Move Feature and Manifest to top-level extensions.

chrome/common/extensions/features/manifest_feature.cc

 // 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.
 
 #include "chrome/common/extensions/features/manifest_feature.h"
 
-#include "chrome/common/extensions/manifest.h"
+#include "extensions/common/manifest.h"
 
 namespace extensions {
 
 ManifestFeature::ManifestFeature() {
 }
 
 ManifestFeature::~ManifestFeature() {
 }
 
 Feature::Availability ManifestFeature::IsAvailableToContext(
@@ skipping 25 matching lines @@
     return name() + ": Manifest features must specify at least one " +
         "value for extension_types.";
   }
 
   if (!GetContexts()->empty())
     return name() + ": Manifest features do not support contexts.";
 
   return std::string();
 }
 
-}  // namespace
+}  // namespace extensions