[Extensions][TaskScheduler] Update ActivityLog for scheduling migration

chrome/browser/extensions/activity_log/activity_log_task_runner.cc

Index: chrome/browser/extensions/activity_log/activity_log_task_runner.cc
diff --git a/chrome/browser/extensions/activity_log/activity_log_task_runner.cc b/chrome/browser/extensions/activity_log/activity_log_task_runner.cc
new file mode 100644
index 0000000000000000000000000000000000000000..7a0dfe8cdd702a470ab5b58eaf3928edc2236833
--- /dev/null
+++ b/chrome/browser/extensions/activity_log/activity_log_task_runner.cc
@@ -0,0 +1,30 @@
+// Copyright 2017 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/extensions/activity_log/activity_log_task_runner.h"
+
+#include "base/sequenced_task_runner.h"
+#include "base/task_scheduler/lazy_task_runner.h"
+
+namespace extensions {
+
+namespace {
+base::TaskRunner* g_task_runner_for_testing = nullptr;
+}
+
+const scoped_refptr<base::TaskRunner> GetActivityLogTaskRunner() {
+  if (g_task_runner_for_testing)
+    return g_task_runner_for_testing;
+
+  static base::LazySequencedTaskRunner task_runner =
+      LAZY_SEQUENCED_TASK_RUNNER_INITIALIZER(
+          base::TaskTraits({base::MayBlock(), base::TaskPriority::BACKGROUND}));
+  return task_runner.Get();
+}
+
+void SetActivityLogTaskRunnerForTesting(base::TaskRunner* task_runner) {
+  g_task_runner_for_testing = task_runner;
+}
+
+}  // namespace extensions