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) {
+    if (!main_thread_only().immediate_work_queue->Empty()) {
+      main_thread_only().time_domain->OnQueueHasImmediateWork(this);
+    } else {
+      base::AutoLock lock(any_thread_lock_);
+      if (!any_thread().immediate_incoming_queue.empty())
+        main_thread_only().time_domain->OnQueueHasImmediateWork(this);

[Sami, 2017/02/21 18:21:02]

Should we call this outside the lock? Thinking about re-entrancy...

[alex clarke (OOO till 29th), 2017/02/21 20:52:30]

Done.

+    }
     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