[renderer] Fix Task Queue Manager trace events.

Adds a missing EndArray() to the TaskQueue::AsValueInto introduced in r321183

Review URL: https://codereview.chromium.org/1027843002

Cr-Commit-Position: refs/heads/master@{#321588}

content/renderer/scheduler/task_queue_manager.cc

@@ -387,6 +387,7 @@ void TaskQueue::AsValueInto(base::trace_event::TracedValue* state) const {
   state->EndArray();
   state->BeginArray("work_queue");
   QueueAsValueInto(work_queue_, state);
+  state->EndArray();
   state->BeginArray("delayed_task_queue");
   QueueAsValueInto(delayed_task_queue_, state);
   state->EndArray();