Remove calls to MessageLoop::current() in ipc.

ipc/ipc_logging.h

Index: ipc/ipc_logging.h
diff --git a/ipc/ipc_logging.h b/ipc/ipc_logging.h
index 523413501d121983f33f1ddfb4dc159788ae9bef..e567921624e9a53533cb448b9762fdb5009fe9a1 100644
--- a/ipc/ipc_logging.h
+++ b/ipc/ipc_logging.h
@@ -14,8 +14,9 @@
 #include <vector>
 
 #include "base/containers/hash_tables.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/singleton.h"
-#include "base/message_loop/message_loop.h"
+#include "base/single_thread_task_runner.h"
 #include "ipc/ipc_export.h"
 
 // Logging function. |name| is a string in ASCII and |params| is a string in
@@ -114,7 +115,7 @@ class IPC_EXPORT Logging {
   bool queue_invoke_later_pending_;
 
   Sender* sender_;
-  base::MessageLoop* main_thread_;
+  scoped_refptr<base::SingleThreadTaskRunner> main_thread_;
 
   Consumer* consumer_;