Update from https://crrev.com/320343

base/test/test_mock_time_task_runner.cc

Index: base/test/test_mock_time_task_runner.cc
diff --git a/base/test/test_mock_time_task_runner.cc b/base/test/test_mock_time_task_runner.cc
index 8e65ccf632ce9ef99c642b4532901ccae4782daf..6bcab8b91f3a52ee535fe5be8195134a16bd1a91 100644
--- a/base/test/test_mock_time_task_runner.cc
+++ b/base/test/test_mock_time_task_runner.cc
@@ -100,6 +100,13 @@ void TestMockTimeTaskRunner::FastForwardUntilNoTasksRemain() {
   ProcessAllTasksNoLaterThan(TimeDelta::Max());
 }
 
+void TestMockTimeTaskRunner::ClearPendingTasks() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  AutoLock scoped_lock(tasks_lock_);
+  while (!tasks_.empty())
+    tasks_.pop();
+}
+
 Time TestMockTimeTaskRunner::Now() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return now_;