Record PendingTaskCount when a backgrounded renderer is suspended.

third_party/WebKit/public/platform/scheduler/base/task_queue.h

Index: third_party/WebKit/public/platform/scheduler/base/task_queue.h
diff --git a/third_party/WebKit/public/platform/scheduler/base/task_queue.h b/third_party/WebKit/public/platform/scheduler/base/task_queue.h
index 6572c35b52659f8ceb07acdb56a2e2286d5d19ca..e34730847fd71557418b342ef8dc37a3250de930 100644
--- a/third_party/WebKit/public/platform/scheduler/base/task_queue.h
+++ b/third_party/WebKit/public/platform/scheduler/base/task_queue.h
@@ -103,6 +103,9 @@ class BLINK_PLATFORM_EXPORT TaskQueue : public base::SingleThreadTaskRunner {
   // Returns true if the queue is completely empty.
   virtual bool IsEmpty() const = 0;
 
+  // Returns the number of pending tasks in the queue.
+  virtual size_t GetNumberOfPendingTasks() const = 0;
+
   // Returns true if the queue has work that's ready to execute now.
   // NOTE: this must be called on the thread this TaskQueue was created by.
   virtual bool HasPendingImmediateWork() const = 0;