Mojo: Add basic logging facilities to environment.

mojo/public/c/environment/logger.h

+// 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.
+
+#ifndef MOJO_PUBLIC_C_ENVIRONMENT_LOGGER_H_
+#define MOJO_PUBLIC_C_ENVIRONMENT_LOGGER_H_
+
+#include <stdint.h>
+
+// |MojoLogLevel|: Used to specify the type of log message. Values are ordered
+// by severity (i.e., higher numerical values are more severe).
+
+typedef int32_t MojoLogLevel;
+
+#ifdef __cplusplus
+const MojoLogLevel MOJO_LOG_LEVEL_VERBOSE = -1;
+const MojoLogLevel MOJO_LOG_LEVEL_INFO = 0;
+const MojoLogLevel MOJO_LOG_LEVEL_WARNING = 1;
+const MojoLogLevel MOJO_LOG_LEVEL_ERROR = 2;
+const MojoLogLevel MOJO_LOG_LEVEL_FATAL = 3;
+#else
+#define MOJO_LOG_LEVEL_INFO ((MojoLogLevel) 0)

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

MOJO_LOG_LEVEL_VERBOSE needed for the C case too?

+#define MOJO_LOG_LEVEL_WARNING ((MojoLogLevel) 1)
+#define MOJO_LOG_LEVEL_ERROR ((MojoLogLevel) 2)
+#define MOJO_LOG_LEVEL_FATAL ((MojoLogLevel) 3)
+#endif
+
+struct MojoLogger {
+  void (*LogMessage)(MojoLogLevel log_level, const char* message);
+};
+
+#endif  // MOJO_PUBLIC_C_ENVIRONMENT_LOGGER_H_