Clean-up coding style

extensions/common/extension_builder.h

 // Copyright 2013 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.
 
 #ifndef EXTENSIONS_COMMON_EXTENSION_BUILDER_H_
 #define EXTENSIONS_COMMON_EXTENSION_BUILDER_H_
 
+#include <string>
+
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "extensions/common/manifest.h"
 #include "extensions/common/value_builder.h"
 
 namespace extensions {
 class Extension;
 
 // An easier way to create extensions than Extension::Create.  The
@@ skipping 33 matching lines @@
   ExtensionBuilder& SetID(const std::string& id);
 
  private:
   base::FilePath path_;
   Manifest::Location location_;
   scoped_ptr<base::DictionaryValue> manifest_;
   int flags_;
   std::string id_;
 };
 
-} // namespace extensions
+}  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_EXTENSION_BUILDER_H_