Introduce ThreadTaskRunnerHandle::OverrideForTesting and TestMockTimeTaskRunner::ScopedContext.

base/threading/post_task_and_reply_impl_unittest.cc

Index: base/threading/post_task_and_reply_impl_unittest.cc
diff --git a/base/threading/post_task_and_reply_impl_unittest.cc b/base/threading/post_task_and_reply_impl_unittest.cc
index 8c6faaf8c0afc9a8d01a999f8238c4ecf8823556..13d5cc98401e02df726cc8e76181f0576b398eb8 100644
--- a/base/threading/post_task_and_reply_impl_unittest.cc
+++ b/base/threading/post_task_and_reply_impl_unittest.cc
@@ -9,7 +9,7 @@
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/test/test_simple_task_runner.h"
-#include "base/threading/sequenced_task_runner_handle.h"
+#include "base/threading/thread_task_runner_handle.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -74,7 +74,7 @@ class MockObject {
 TEST(PostTaskAndReplyImplTest, PostTaskAndReply) {
   scoped_refptr<TestSimpleTaskRunner> post_runner(new TestSimpleTaskRunner);
   scoped_refptr<TestSimpleTaskRunner> reply_runner(new TestSimpleTaskRunner);
-  SequencedTaskRunnerHandle sequenced_task_runner_handle(reply_runner);
+  ThreadTaskRunnerHandle task_runner_handle(reply_runner);
 
   testing::StrictMock<MockObject> mock_object;
   bool delete_flag = false;