Use a direct include of strings headers in chrome/common/, part 1.

chrome/common/extensions/manifest.h

 // 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.
 
 #ifndef CHROME_COMMON_EXTENSIONS_MANIFEST_H_
 #define CHROME_COMMON_EXTENSIONS_MANIFEST_H_
 
 #include <map>
+#include <set>
 #include <string>
-#include <set>
 
 #include "base/memory/scoped_ptr.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "base/values.h"
 
 namespace extensions {
 struct InstallWarning;
 
 // Wraps the DictionaryValue form of extension's manifest. Enforces access to
 // properties of the manifest using ManifestFeatureProvider.
 class Manifest {
  public:
   // What an extension was loaded from.
@@ skipping 144 matching lines @@
   scoped_ptr<base::DictionaryValue> value_;
 
   Type type_;
 
   DISALLOW_COPY_AND_ASSIGN(Manifest);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_MANIFEST_H_