[extensions] Replace MessageLoopProxy usage with ThreadTaskRunnerHandle

extensions/common/one_shot_event_unittest.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "extensions/common/one_shot_event.h"
 
 #include "base/bind.h"
 #include "base/run_loop.h"
+#include "base/single_thread_task_runner.h"
 #include "base/test/test_simple_task_runner.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace extensions {
 
 namespace {
 
 void Increment(int* i) { ++*i; }
 
 TEST(OneShotEventTest, RecordsSignal) {
@@ skipping 50 matching lines @@
   EXPECT_EQ(0, runner_i);
   runner->RunPendingTasks();
   EXPECT_EQ(1, runner_i);
   EXPECT_EQ(0, loop_i);
   base::RunLoop().RunUntilIdle();
   EXPECT_EQ(1, loop_i);
 }
 
 void CheckSignaledAndPostIncrement(
     OneShotEvent* event,
-    const scoped_refptr<base::TaskRunner>& runner,
+    const scoped_refptr<base::SingleThreadTaskRunner>& runner,
     int* i) {
   EXPECT_TRUE(event->is_signaled());
   event->Post(FROM_HERE, base::Bind(&Increment, i), runner);
 }
 
 TEST(OneShotEventTest, IsSignaledAndPostsFromCallbackWork) {
   OneShotEvent event;
   scoped_refptr<base::TestSimpleTaskRunner> runner(
       new base::TestSimpleTaskRunner);
   int i = 0;
@@ skipping 12 matching lines @@
   EXPECT_EQ(1U, runner->GetPendingTasks().size());
   EXPECT_EQ(0, i);
   runner->RunPendingTasks();
   // Increment has run.
   EXPECT_EQ(0U, runner->GetPendingTasks().size());
   EXPECT_EQ(1, i);
 }
 
 }  // namespace
 }  // namespace extensions