Move nullable_string16.h to the string subdirectory.

webkit/browser/dom_storage/dom_storage_area.h

Index: webkit/browser/dom_storage/dom_storage_area.h
diff --git a/webkit/browser/dom_storage/dom_storage_area.h b/webkit/browser/dom_storage/dom_storage_area.h
index fdd7fa2e372b6399c9a137fb5cbc75d687bcab2b..6f407e9d7e3d575d4b5e49d8c07c2ca802541032 100644
--- a/webkit/browser/dom_storage/dom_storage_area.h
+++ b/webkit/browser/dom_storage/dom_storage_area.h
@@ -9,7 +9,7 @@
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
-#include "base/nullable_string16.h"
+#include "base/strings/nullable_string16.h"
 #include "base/strings/string16.h"
 #include "googleurl/src/gurl.h"
 #include "webkit/common/dom_storage/dom_storage_types.h"
@@ -52,10 +52,10 @@ class WEBKIT_STORAGE_EXPORT DomStorageArea
   void ExtractValues(ValuesMap* map);
 
   unsigned Length();
-  NullableString16 Key(unsigned index);
-  NullableString16 GetItem(const base::string16& key);
+  base::NullableString16 Key(unsigned index);
+  base::NullableString16 GetItem(const base::string16& key);
   bool SetItem(const base::string16& key, const base::string16& value,
-               NullableString16* old_value);
+               base::NullableString16* old_value);
   bool RemoveItem(const base::string16& key, base::string16* old_value);
   bool Clear();
   void FastClear();