Mojo: Add basic logging facilities to environment.

mojo/environment/default_logger_impl.h

Index: mojo/environment/default_logger_impl.h
diff --git a/mojo/environment/default_async_waiter_impl.h b/mojo/environment/default_logger_impl.h
similarity index 51%
copy from mojo/environment/default_async_waiter_impl.h
copy to mojo/environment/default_logger_impl.h
index 8e697cb42572b24d6559d50beee2cbffd144203e..c87a7276e434c205b99180516bacb8954d0d2a4f 100644
--- a/mojo/environment/default_async_waiter_impl.h
+++ b/mojo/environment/default_logger_impl.h
@@ -2,18 +2,18 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef MOJO_ENVIRONMENT_DEFAULT_ASYNC_WAITER_IMPL_H_
-#define MOJO_ENVIRONMENT_DEFAULT_ASYNC_WAITER_IMPL_H_
+#ifndef MOJO_ENVIRONMENT_DEFAULT_LOGGER_IMPL_H_
+#define MOJO_ENVIRONMENT_DEFAULT_LOGGER_IMPL_H_
 
 #include "mojo/environment/mojo_environment_impl_export.h"
-#include "mojo/public/c/environment/async_waiter.h"
+#include "mojo/public/c/environment/logger.h"
 
 namespace mojo {
 namespace internal {
 
-MOJO_ENVIRONMENT_IMPL_EXPORT MojoAsyncWaiter* GetDefaultAsyncWaiterImpl();
+MOJO_ENVIRONMENT_IMPL_EXPORT const MojoLogger* GetDefaultLoggerImpl();
 
 }  // namespace internal
 }  // namespace mojo
 
-#endif  // MOJO_ENVIRONMENT_DEFAULT_ASYNC_WAITER_IMPL_H_
+#endif  // MOJO_ENVIRONMENT_DEFAULT_LOGGER_IMPL_H_