Record PendingTaskCount when a backgrounded renderer is suspended.

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/trace_event/blame_context.h"
 #include "platform/scheduler/base/task_queue_manager.h"
 #include "platform/scheduler/base/task_queue_manager_delegate.h"
 #include "platform/scheduler/base/time_domain.h"
@@ skipping 303 matching lines @@
   if (!main_thread_only().delayed_work_queue->Empty() ||
       !main_thread_only().delayed_incoming_queue.empty() ||
       !main_thread_only().immediate_work_queue->Empty()) {
     return false;
   }
 
   base::AutoLock lock(any_thread_lock_);
   return any_thread().immediate_incoming_queue.empty();
 }
 
+size_t TaskQueueImpl::GetNumberOfPendingTasks() const {
+  size_t task_count = 0;
+  task_count += main_thread_only().delayed_work_queue->Size();
+  task_count += main_thread_only().delayed_incoming_queue.size();
+  task_count += main_thread_only().immediate_work_queue->Size();
+
+  base::AutoLock lock(any_thread_lock_);
+  task_count += any_thread().immediate_incoming_queue.size();
+  return task_count;
+}
+
 bool TaskQueueImpl::HasPendingImmediateWork() const {
   // Any work queue tasks count as immediate work.
   if (!main_thread_only().delayed_work_queue->Empty() ||
       !main_thread_only().immediate_work_queue->Empty()) {
     return true;
   }
 
   // Tasks on |delayed_incoming_queue| that could run now, count as
   // immediate work.
   if (!main_thread_only().delayed_incoming_queue.empty() &&
@@ skipping 362 matching lines @@
   state->SetBoolean("is_cancelled", task.task.IsCancelled());
   state->SetDouble(
       "delayed_run_time",
       (task.delayed_run_time - base::TimeTicks()).InMicroseconds() / 1000.0L);
   state->EndDictionary();
 }
 
 }  // namespace internal
 }  // namespace scheduler
 }  // namespace blink