Record PendingTaskCount when a backgrounded renderer is suspended.

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

 // Copyright 2014 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_manager.h"
 
 #include <queue>
 #include <set>
 
 #include "base/bind.h"
@@ skipping 408 matching lines @@
 }
 
 internal::EnqueueOrder TaskQueueManager::GetNextSequenceNumber() {
   return enqueue_order_generator_.GenerateNext();
 }
 
 LazyNow TaskQueueManager::CreateLazyNow() const {
   return LazyNow(delegate_.get());
 }
 
+size_t TaskQueueManager::GetNumberOfPendingTasks() const {
+  size_t task_count = 0;
+  for (auto& queue : queues_)
+    task_count += queue->GetNumberOfPendingTasks();
+  return task_count;
+}
+
 std::unique_ptr<base::trace_event::ConvertableToTraceFormat>
 TaskQueueManager::AsValueWithSelectorResult(
     bool should_run,
     internal::WorkQueue* selected_work_queue) const {
   DCHECK(main_thread_checker_.CalledOnValidThread());
   std::unique_ptr<base::trace_event::TracedValue> state(
       new base::trace_event::TracedValue());
   state->BeginArray("queues");
   for (auto& queue : queues_)
     queue->AsValueInto(state.get());
@@ skipping 26 matching lines @@
   DCHECK(main_thread_checker_.CalledOnValidThread());
   DCHECK(!work_queue->Empty());
   if (observer_) {
     observer_->OnTriedToExecuteBlockedTask(*work_queue->task_queue(),
                                            *work_queue->GetFrontTask());
   }
 }
 
 }  // namespace scheduler
 }  // namespace blink