(Merge m52) Fix a bug with throttling and timer queue suspension

components/scheduler/renderer/throttling_helper.h

Index: components/scheduler/renderer/throttling_helper.h
diff --git a/components/scheduler/renderer/throttling_helper.h b/components/scheduler/renderer/throttling_helper.h
index df750757681fcb174d12bdf0809f547bfe867a97..2930f1ba02081d1a8d1bae189c5b4ac6a6410c29 100644
--- a/components/scheduler/renderer/throttling_helper.h
+++ b/components/scheduler/renderer/throttling_helper.h
@@ -30,6 +30,14 @@ class SCHEDULER_EXPORT ThrottlingHelper : public TimeDomain::Observer {
   void OnTimeDomainHasImmediateWork() override;
   void OnTimeDomainHasDelayedWork() override;
 
+  // The purpose of this method is to make sure thottling doesn't conflict with
+  // enabling/disabling the queue for policy reasons.
+  // If |task_queue| is throttled then the ThrottlingHelper remembers the
+  // |enabled| setting.  In addition if |enabled| is false then the queue is
+  // immediatly disabled.  Otherwise if |task_queue| not throttled then
+  // TaskQueue::SetEnabled(enabled) is called.
+  void SetQueueEnabled(TaskQueue* task_queue, bool enabled);
+
   // Increments the throttled refcount and causes |task_queue| to be throttled
   // if its not already throttled.
   void IncreaseThrottleRefCount(TaskQueue* task_queue);
@@ -49,7 +57,16 @@ class SCHEDULER_EXPORT ThrottlingHelper : public TimeDomain::Observer {
   const scoped_refptr<TaskQueue>& task_runner() const { return task_runner_; }
 
  private:
-  using TaskQueueMap = std::map<TaskQueue*, size_t>;
+  struct Metadata {
+    Metadata() : throttling_ref_count(0), enabled(false) {}
+
+    Metadata(size_t ref_count, bool is_enabled)
+        : throttling_ref_count(ref_count), enabled(is_enabled) {}
+
+    size_t throttling_ref_count;
+    bool enabled;
+  };
+  using TaskQueueMap = std::map<TaskQueue*, Metadata>;
 
   void PumpThrottledTasks();