Add explicit base namespace to string16 users.

chrome/common/extensions/manifest_tests/extension_manifests_initvalue_unittest.cc

 // 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.
 
 #include "base/i18n/rtl.h"
 #include "base/path_service.h"
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/common/chrome_paths.h"
 #include "chrome/common/extensions/manifest_tests/extension_manifest_test.h"
 #include "chrome/common/extensions/manifest_url_handler.h"
@@ skipping 135 matching lines @@
   gtk_widget_set_default_direction(GTK_TEXT_DIR_RTL);
 #else
   std::string locale = l10n_util::GetApplicationLocale("");
   base::i18n::SetICUDefaultLocale("he");
 #endif
 
   // No strong RTL characters in name.
   scoped_refptr<Extension> extension(LoadAndExpectSuccess(
       "init_valid_name_no_rtl.json"));
 
-  string16 localized_name(ASCIIToUTF16("Dictionary (by Google)"));
+  base::string16 localized_name(ASCIIToUTF16("Dictionary (by Google)"));
   base::i18n::AdjustStringForLocaleDirection(&localized_name);
   EXPECT_EQ(localized_name, UTF8ToUTF16(extension->name()));
 
   // Strong RTL characters in name.
   extension = LoadAndExpectSuccess("init_valid_name_strong_rtl.json");
 
   localized_name = WideToUTF16(L"Dictionary (\x05D1\x05D2" L" Google)");
   base::i18n::AdjustStringForLocaleDirection(&localized_name);
   EXPECT_EQ(localized_name, UTF8ToUTF16(extension->name()));
 
   // Reset locale.
 #if defined(TOOLKIT_GTK)
   gtk_widget_set_default_direction(gtk_dir);
 #else
   base::i18n::SetICUDefaultLocale(locale);
 #endif
 }
 
 }  // namespace extensions