Add RetainedRef uses where needed.

This patch adds RetainedRef uses where they are required. These
changes will be required when we remove automatic unwrapping of
scoped_refptrs in Bind.

Please see the bug for more context.

[email protected], [email protected], [email protected]
BUG=589048

Review URL: https://codereview.chromium.org/1815363002

Cr-Commit-Position: refs/heads/master@{#382371}
diff --git a/ipc/ipc_sync_channel.cc b/ipc/ipc_sync_channel.cc
index d194211..445a60e 100644
--- a/ipc/ipc_sync_channel.cc
+++ b/ipc/ipc_sync_channel.cc
@@ -80,7 +80,7 @@
     if (!was_task_pending) {
       listener_task_runner_->PostTask(
           FROM_HERE, base::Bind(&ReceivedSyncMsgQueue::DispatchMessagesTask,
-                                this, scoped_refptr<SyncContext>(context)));
+                                this, base::RetainedRef(context)));
     }
   }