Remove 'using base::string16;' from base/strings/string16.h and remove temporary

base/test/test_reg_util_win.h

 // Copyright (c) 2011 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 BASE_TEST_TEST_REG_UTIL_H_
 #define BASE_TEST_TEST_REG_UTIL_H_
 
 // Registry utility functions used only by tests.
 
 #include "base/basictypes.h"
@@ skipping 20 matching lines @@
 //     two RegistryOverrideManagers created with the same timestamp.
 class RegistryOverrideManager {
  public:
   RegistryOverrideManager();
   ~RegistryOverrideManager();
 
   // Override the given registry hive using a temporary key named by temp_name
   // under the temporary test key path. There is no need to randomize
   // |override_name|, as a random parent key is generated. Multiple overrides to
   // the same hive are not supported and lead to undefined behavior.
-  void OverrideRegistry(HKEY override, const string16& override_name);
+  void OverrideRegistry(HKEY override, const base::string16& override_name);
 
  private:
   friend class RegistryOverrideManagerTest;
 
   // Keeps track of one override.
   class ScopedRegistryKeyOverride {
    public:
-    ScopedRegistryKeyOverride(HKEY override, const string16& key_path);
+    ScopedRegistryKeyOverride(HKEY override, const base::string16& key_path);
     ~ScopedRegistryKeyOverride();
 
    private:
     HKEY override_;
     base::win::RegKey temp_key_;
 
     DISALLOW_COPY_AND_ASSIGN(ScopedRegistryKeyOverride);
   };
 
   // Used for testing only.
   RegistryOverrideManager(const base::Time& timestamp,
-                          const string16& test_key_root);
+                          const base::string16& test_key_root);
 
   base::Time timestamp_;
-  string16 guid_;
+  base::string16 guid_;
 
-  string16 test_key_root_;
+  base::string16 test_key_root_;
   ScopedVector<ScopedRegistryKeyOverride> overrides_;
 
   DISALLOW_COPY_AND_ASSIGN(RegistryOverrideManager);
 };
 
 // Generates a temporary key path that will be eventually deleted
 // automatically if the process crashes.
-string16 GenerateTempKeyPath();
+base::string16 GenerateTempKeyPath();
 
 }  // namespace registry_util
 
 #endif  // BASE_TEST_TEST_REG_UTIL_H_