[scheduler] Split lock in TaskQueueImpl.

third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h

Index: third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
diff --git a/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h b/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
index 79503356b851cf354ffc12f40d93ef4b862e6fac..3adeeced197489a323047d31e2dbd15a77218580 100644
--- a/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
+++ b/third_party/WebKit/Source/platform/scheduler/base/task_queue_impl.h
@@ -253,8 +253,6 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
     // main thread, so it should be locked before accessing from other threads.
     TaskQueueManager* task_queue_manager;
     TimeDomain* time_domain;
-
-    WTF::Deque<Task> immediate_incoming_queue;
   };
 
   struct MainThreadOnly {
@@ -318,7 +316,7 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
   // Can be called from any thread.
   WTF::Deque<TaskQueueImpl::Task> TakeImmediateIncomingQueue();
 
-  void TraceQueueSize(bool is_locked) const;
+  void TraceQueueSize() const;
   static void QueueAsValueInto(const WTF::Deque<Task>& queue,
                                base::trace_event::TracedValue* state);
   static void QueueAsValueInto(const std::priority_queue<Task>& queue,
@@ -359,6 +357,17 @@ class BLINK_PLATFORM_EXPORT TaskQueueImpl final : public TaskQueue {
     return main_thread_only_;
   }
 
+  mutable base::Lock immediate_incoming_queue_lock_;
+  WTF::Deque<Task> immediate_incoming_queue_;
+  WTF::Deque<Task>& immediate_incoming_queue() {
+    immediate_incoming_queue_lock_.AssertAcquired();
+    return immediate_incoming_queue_;
+  }
+  const WTF::Deque<Task>& immediate_incoming_queue() const {
+    immediate_incoming_queue_lock_.AssertAcquired();
+    return immediate_incoming_queue_;
+  }
+
   const bool should_monitor_quiescence_;
   const bool should_notify_observers_;
   const bool should_report_when_execution_blocked_;