base: Support using (D)CHECK on scoped enums.

base/logging.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/logging.h"
 
 #include <limits.h>
 #include <stdint.h>
 
 #include "base/macros.h"
@@ skipping 436 matching lines @@
     const int&, const int&, const char* names);
 template std::string* MakeCheckOpString<unsigned long, unsigned long>(
     const unsigned long&, const unsigned long&, const char* names);
 template std::string* MakeCheckOpString<unsigned long, unsigned int>(
     const unsigned long&, const unsigned int&, const char* names);
 template std::string* MakeCheckOpString<unsigned int, unsigned long>(
     const unsigned int&, const unsigned long&, const char* names);
 template std::string* MakeCheckOpString<std::string, std::string>(
     const std::string&, const std::string&, const char* name);
 
-template <>
-void MakeCheckOpValueString(std::ostream* os, const std::nullptr_t& p) {
+void MakeCheckOpValueString(std::ostream* os, std::nullptr_t p) {
   (*os) << "nullptr";
 }
 
 #if !defined(NDEBUG)
 // Displays a message box to the user with the error message in it.
 // Used for fatal messages, where we close the app simultaneously.
 // This is for developers only; we don't use this in circumstances
 // (like release builds) where users could see it, since users don't
 // understand these messages anyway.
 void DisplayDebugMessageInDialog(const std::string& str) {
@@ skipping 444 matching lines @@
 BASE_EXPORT void LogErrorNotReached(const char* file, int line) {
   LogMessage(file, line, LOG_ERROR).stream()
       << "NOTREACHED() hit.";
 }
 
 }  // namespace logging
 
 std::ostream& std::operator<<(std::ostream& out, const wchar_t* wstr) {
   return out << (wstr ? base::WideToUTF8(wstr) : std::string());
 }