Mojo: Add basic logging facilities to environment.

mojo/public/cpp/environment/default_logger.h

Index: mojo/public/cpp/environment/default_logger.h
diff --git a/mojo/public/cpp/environment/default_logger.h b/mojo/public/cpp/environment/default_logger.h
new file mode 100644
index 0000000000000000000000000000000000000000..b0223937666d40c69a7086dcd83310ac9583f7e2
--- /dev/null
+++ b/mojo/public/cpp/environment/default_logger.h
@@ -0,0 +1,17 @@
+// 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_CPP_ENVIRONMENT_DEFAULT_LOGGER_H_
+#define MOJO_PUBLIC_CPP_ENVIRONMENT_DEFAULT_LOGGER_H_
+
+#include "mojo/public/c/environment/logger.h"
+
+namespace mojo {
+
+// Returns a default implementation of |MojoLogger|.
+const MojoLogger* GetDefaultLogger();
+
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_ENVIRONMENT_DEFAULT_LOGGER_H_