Remove remaining use of the deprecated MessageLoopProxy

mojo/runner/child_process.cc

Index: mojo/runner/child_process.cc
diff --git a/mojo/runner/child_process.cc b/mojo/runner/child_process.cc
index a7be4ea22efb23b871ea7f36771075a39810ee83..b89e322b57df432a7e7194bea1916a787819d080 100644
--- a/mojo/runner/child_process.cc
+++ b/mojo/runner/child_process.cc
@@ -17,6 +17,7 @@
 #include "base/message_loop/message_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "base/synchronization/waitable_event.h"
+#include "base/thread_task_runner_handle.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_checker.h"
 #include "mojo/common/message_pump_mojo.h"
@@ -194,7 +195,7 @@ class ChildControllerImpl : public ChildController, public ErrorHandler {
         platform_channel.Pass(), app_context->io_runner(),
         base::Bind(&ChildControllerImpl::DidCreateChannel,
                    base::Unretained(impl.get())),
-        base::MessageLoopProxy::current()));
+        base::ThreadTaskRunnerHandle::Get()));
 
     impl->Bind(host_message_pipe.Pass());