Introduce ThreadTaskRunnerHandle::OverrideForTesting and TestMockTimeTaskRunner::ScopedContext.

chrome/browser/chromeos/policy/server_backed_state_keys_broker_unittest.cc

 // Copyright 2014 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 "chrome/browser/chromeos/policy/server_backed_state_keys_broker.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 95 matching lines @@
                      base::Unretained(this)));
   base::RunLoop().RunUntilIdle();
   EXPECT_TRUE(updated_);
   ExpectGood();
 
   // Update callbacks get fired if the keys change.
   state_keys_.erase(state_keys_.begin());
   state_keys_.push_back("4");
   fake_session_manager_client_.set_server_backed_state_keys(state_keys_);
   updated_ = false;
-  task_runner_->RunPendingTasks();
-  base::RunLoop().RunUntilIdle();
+  task_runner_->RunUntilIdle();
   EXPECT_TRUE(updated_);
   ExpectGood();
 
   // No update callback if the keys are unchanged.
   updated_ = false;
-  task_runner_->RunPendingTasks();
-  base::RunLoop().RunUntilIdle();
+  task_runner_->RunUntilIdle();
   EXPECT_FALSE(updated_);
   ExpectGood();
 }
 
 TEST_F(ServerBackedStateKeysBrokerTest, Request) {
   broker_.RequestStateKeys(
       base::Bind(&ServerBackedStateKeysBrokerTest::HandleStateKeysCallback,
                  base::Unretained(this)));
   base::RunLoop().RunUntilIdle();
   ExpectGood();
   EXPECT_TRUE(callback_invoked_);
   EXPECT_EQ(state_keys_, callback_state_keys_);
 }
 
 TEST_F(ServerBackedStateKeysBrokerTest, RequestFailure) {
   fake_session_manager_client_.set_server_backed_state_keys(
       std::vector<std::string>());
 
   broker_.RequestStateKeys(
       base::Bind(&ServerBackedStateKeysBrokerTest::HandleStateKeysCallback,
                  base::Unretained(this)));
   base::RunLoop().RunUntilIdle();
   EXPECT_TRUE(callback_invoked_);
   EXPECT_TRUE(callback_state_keys_.empty());
 }
 
 }  // namespace policy