Revert of Allow std::unordered_*.

base/strings/string16_unittest.cc

 // Copyright 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.
 
 #include <sstream>
-#include <unordered_set>
 
 #include "base/strings/string16.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 
+#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;
     stream << "Empty '" << string16() << "' standard '"
            << string16(ASCIIToUTF16("Hello, world")) << "'";
     EXPECT_STREQ("Empty '' standard 'Hello, world'",
                  stream.str().c_str());
@@ skipping 20 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());
   }
 }
 
-TEST(String16Test, Hash) {
-  string16 str1 = ASCIIToUTF16("hello");
-  string16 str2 = ASCIIToUTF16("world");
-
-  std::unordered_set<string16> set;
-
-  set.insert(str1);
-  EXPECT_EQ(1u, set.count(str1));
-  EXPECT_EQ(0u, set.count(str2));
-}
+#endif
 
 }  // namespace base