Fix potential DCHECK in TaskQueueThrottler::IncreaseThrottleRefCount

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

 // Copyright 2015 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 "platform/scheduler/base/task_queue_impl.h"
 
 #include "base/format_macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/trace_event/blame_context.h"
@@ skipping 785 matching lines @@
   bool is_enabled = IsQueueEnabled();
   if (was_enabled != is_enabled)
     EnableOrDisableWithSelector(is_enabled);
 }
 
 void TaskQueueImpl::EnableOrDisableWithSelector(bool enable) {
   if (!main_thread_only().task_queue_manager)
     return;
 
   if (enable) {
+    // Check if there's any immediate work on either queue.
+    bool immediate_queues_empty =
+        main_thread_only().immediate_work_queue->Empty();
+    if (immediate_queues_empty) {
+      base::AutoLock lock(any_thread_lock_);
+      immediate_queues_empty = any_thread().immediate_incoming_queue.empty();
+    }
+    // Avoid holding the lock while we fire the notification.
+    if (!immediate_queues_empty)
+      main_thread_only().time_domain->OnQueueHasImmediateWork(this);
+
     if (!main_thread_only().delayed_incoming_queue.empty()) {
       main_thread_only().time_domain->ScheduleDelayedWork(
           this,
           main_thread_only().delayed_incoming_queue.top().delayed_run_time,
           main_thread_only().time_domain->Now());
     }
     // Note the selector calls TaskQueueManager::OnTaskQueueEnabled which posts
     // a DoWork if needed.
     main_thread_only().task_queue_manager->selector_.EnableQueue(this);
   } else {
@@ skipping 45 matching lines @@
 
 void TaskQueueImpl::PushImmediateIncomingTaskForTest(
     TaskQueueImpl::Task&& task) {
   base::AutoLock lock(any_thread_lock_);
   any_thread().immediate_incoming_queue.push_back(std::move(task));
 }
 
 }  // namespace internal
 }  // namespace scheduler
 }  // namespace blink