Use a direct include of utf_string_conversions.h in android_webview/, apps/, ash/, base/.

base/string16_unittest.cc

 // Copyright (c) 2009 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 <sstream>
 
 #include "base/string16.h"
-#include "base/utf_string_conversions.h"
+#include "base/strings/utf_string_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 #if defined(WCHAR_T_IS_UTF32)
 
 // We define a custom operator<< for string16 so we can use it with logging.
 // This tests that conversion.
 TEST(String16Test, OutputStream) {
   // Basic stream test.
   {
     std::ostringstream stream;
@@ skipping 25 matching lines @@
     std::ostringstream stream;
     stream << initial_surrogate << "," << final_surrogate << ","
            << surrogate_pair << "," << unterminated_surrogate;
 
     EXPECT_STREQ("\xef\xbf\xbd,\xef\xbf\xbd,\xf0\x90\x8c\x80z,\xef\xbf\xbds",
                  stream.str().c_str());
   }
 }
 
 #endif