Mojo: Add basic logging facilities to environment.

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/default_logger.h"
+
+#include <stdio.h>
+#include <stdlib.h>  // For |abort()|.
+
+namespace mojo {
+namespace {
+
+const char* GetLogLevelString(MojoLogLevel log_level) {
+  if (log_level < MOJO_LOG_LEVEL_VERBOSE)
+    return "VERBOSE";
+  switch (log_level) {
+    case MOJO_LOG_LEVEL_VERBOSE:
+      return "VERBOSE";
+    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) {
+  // TODO(vtl): Add timestamp also?
+  fprintf(stderr, "%s:%s\n", GetLogLevelString(log_level), message);

[darin (slow to review), 2014/06/14 06:08:23]

nit: it might be nice to add a space after the colon for readability.

ERROR: Foo
WARNING: Bar

+  if (log_level >= MOJO_LOG_LEVEL_FATAL)
+    abort();
+}
+
+const MojoLogger kDefaultLogger = {
+  LogMessage
+};
+
+}  // namespace
+
+const MojoLogger* GetDefaultLogger() {
+  return &kDefaultLogger;
+}
+
+}  // namespace mojo