Mojo: Add logging macros (and supporting code) for use in mojo/public/cpp.

mojo/public/cpp/environment/lib/default_logger.cc

 // Copyright 2014 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 "mojo/public/cpp/environment/lib/default_logger.h"
 
 #include <stdio.h>
 #include <stdlib.h>  // For |abort()|.
 
 #include <algorithm>
 
 #include "mojo/public/c/environment/logger.h"
 
 namespace mojo {
 
 namespace {
 
 MojoLogLevel g_minimum_log_level = MOJO_LOG_LEVEL_INFO;
 
 const char* GetLogLevelString(MojoLogLevel log_level) {
-  if (log_level < MOJO_LOG_LEVEL_VERBOSE)
-    return "VERBOSE";
+  if (log_level <= MOJO_LOG_LEVEL_VERBOSE-3)
+    return "VERBOSE4+";
   switch (log_level) {
+    case MOJO_LOG_LEVEL_VERBOSE-2:
+      return "VERBOSE3";
+    case MOJO_LOG_LEVEL_VERBOSE-1:
+      return "VERBOSE2";
     case MOJO_LOG_LEVEL_VERBOSE:
-      return "VERBOSE";
+      return "VERBOSE1";
     case MOJO_LOG_LEVEL_INFO:
       return "INFO";
     case MOJO_LOG_LEVEL_WARNING:
       return "WARNING";
     case MOJO_LOG_LEVEL_ERROR:
       return "ERROR";
   }
   // Consider everything higher to be fatal.
   return "FATAL";
 }
 
 void LogMessage(MojoLogLevel log_level, const char* message) {
   if (log_level < g_minimum_log_level)
     return;
 
   // TODO(vtl): Add timestamp also?
-  fprintf(stderr, "%s:%s\n", GetLogLevelString(log_level), message);
+  fprintf(stderr, "%s: %s\n", GetLogLevelString(log_level), message);
   if (log_level >= MOJO_LOG_LEVEL_FATAL)
     abort();
 }
 
 MojoLogLevel GetMinimumLogLevel() {
   return g_minimum_log_level;
 }
 
 void SetMinimumLogLevel(MojoLogLevel minimum_log_level) {
   g_minimum_log_level = std::min(minimum_log_level, MOJO_LOG_LEVEL_FATAL);
 }
 
 }  // namespace
 
 namespace internal {
 
 const MojoLogger kDefaultLogger = {
   LogMessage,
   GetMinimumLogLevel,
   SetMinimumLogLevel
 };
 
 }  // namespace internal
 
 }  // namespace mojo