Remove remaining use of the deprecated MessageLoopProxy

mojo/common/handle_watcher.cc

Index: mojo/common/handle_watcher.cc
diff --git a/mojo/common/handle_watcher.cc b/mojo/common/handle_watcher.cc
index 79cdcdb616b7e8cc5c1b69603b945b52f06ced65..6bff0cd1a8981bfdcb190981d6d4b7aa93b88915 100644
--- a/mojo/common/handle_watcher.cc
+++ b/mojo/common/handle_watcher.cc
@@ -14,9 +14,10 @@
 #include "base/memory/singleton.h"
 #include "base/memory/weak_ptr.h"
 #include "base/message_loop/message_loop.h"
-#include "base/message_loop/message_loop_proxy.h"
+#include "base/single_thread_task_runner.h"
 #include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
+#include "base/thread_task_runner_handle.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/time/time.h"
@@ -41,16 +42,14 @@ base::TimeTicks MojoDeadlineToTimeTicks(MojoDeadline deadline) {
 // Tracks the data for a single call to Start().
 struct WatchData {
   WatchData()
-      : id(0),
-        handle_signals(MOJO_HANDLE_SIGNAL_NONE),
-        message_loop(NULL) {}
+      : id(0), handle_signals(MOJO_HANDLE_SIGNAL_NONE), task_runner(NULL) {}
 
   WatcherID id;
   Handle handle;
   MojoHandleSignals handle_signals;
   base::TimeTicks deadline;
   base::Callback<void(MojoResult)> callback;
-  scoped_refptr<base::MessageLoopProxy> message_loop;
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner;
 };
 
 // WatcherBackend --------------------------------------------------------------
@@ -124,7 +123,7 @@ void WatcherBackend::RemoveAndNotify(const Handle& handle,
   handle_to_data_.erase(handle);
   MessagePumpMojo::current()->RemoveHandler(handle);
 
-  data.message_loop->PostTask(FROM_HERE, base::Bind(data.callback, result));
+  data.task_runner->PostTask(FROM_HERE, base::Bind(data.callback, result));
 }
 
 bool WatcherBackend::GetMojoHandleByWatcherID(WatcherID watcher_id,
@@ -238,9 +237,7 @@ WatcherID WatcherThreadManager::StartWatching(
   request_data.start_data.callback = callback;
   request_data.start_data.handle_signals = handle_signals;
   request_data.start_data.deadline = deadline;
-  request_data.start_data.message_loop = base::MessageLoopProxy::current();
-  DCHECK_NE(static_cast<base::MessageLoopProxy*>(NULL),
-            request_data.start_data.message_loop.get());
+  request_data.start_data.task_runner = base::ThreadTaskRunnerHandle::Get();
   AddRequest(request_data);
   return request_data.start_data.id;
 }
@@ -280,7 +277,7 @@ void WatcherThreadManager::AddRequest(const RequestData& data) {
       return;
   }
   // We own |thread_|, so it's safe to use Unretained() here.
-  thread_.message_loop()->PostTask(
+  thread_.task_runner()->PostTask(
       FROM_HERE,
       base::Bind(&WatcherThreadManager::ProcessRequestsOnBackendThread,
                  base::Unretained(this)));