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

chrome/common/extensions/manifest_handler.h

 // Copyright (c) 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 CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLER_H_
 #define CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLER_H_
 
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/lazy_instance.h"
 #include "base/memory/linked_ptr.h"
-#include "base/string16.h"
+#include "base/strings/string16.h"
 #include "chrome/common/extensions/manifest.h"
 
 namespace extensions {
 class Extension;
 
 // An interface for clients that recognize and parse keys in extension
 // manifests.
 class ManifestHandler {
  public:
   ManifestHandler();
@@ skipping 97 matching lines @@
 
   // The priority for each manifest handler. Handlers with lower priority
   // values are evaluated first.
   ManifestHandlerPriorityMap priority_map_;
   bool is_sorted_;
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_COMMON_EXTENSIONS_MANIFEST_HANDLER_H_