[sync] Replace MessageLoopProxy usage with ThreadTaskRunnerHandle

sync/internal_api/public/util/weak_handle.h

Index: sync/internal_api/public/util/weak_handle.h
diff --git a/sync/internal_api/public/util/weak_handle.h b/sync/internal_api/public/util/weak_handle.h
index c299be719c9f63ee5680b6525b1b57f2abbb1eb0..7a11a156536f2ae158248b8800b58cf7d56b95ae 100644
--- a/sync/internal_api/public/util/weak_handle.h
+++ b/sync/internal_api/public/util/weak_handle.h
@@ -58,12 +58,9 @@
 #include "base/logging.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
+#include "base/single_thread_task_runner.h"
 #include "sync/base/sync_export.h"
 
-namespace base {
-class MessageLoopProxy;
-}  // namespace base
-
 namespace tracked_objects {
 class Location;
 }  // namespace tracked_objects
@@ -118,7 +115,7 @@ class SYNC_EXPORT WeakHandleCoreBase {
 
  private:
   // May be used on any thread.
-  const scoped_refptr<base::MessageLoopProxy> owner_loop_proxy_;
+  const scoped_refptr<base::SingleThreadTaskRunner> owner_loop_task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(WeakHandleCoreBase);
 };