[scheduler] Add TaskQueue::Observer

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 c57d23737a45a6631b7991d86b23c51ebe1f14ea..fae92bf351882e38422ff24a6595be479261e805 100644
--- a/third_party/WebKit/public/platform/scheduler/base/task_queue.h
+++ b/third_party/WebKit/public/platform/scheduler/base/task_queue.h
@@ -27,6 +27,20 @@ class BLINK_PLATFORM_EXPORT TaskQueue : public base::SingleThreadTaskRunner {
  public:
   TaskQueue() {}
 
+  class BLINK_PLATFORM_EXPORT Observer {
+   public:
+    virtual ~Observer() {}
+
+    // Notify observer that wake_up has changed. |next_wakeup| can be in the

[Sami, 2017/04/05 13:16:52]

s/wake_up/the time at which this queue wants to run the next task/

[altimin, 2017/04/05 13:55:18]

Done.

+    // past (e.g. base::TimeTicks() can be used to notify about immediate

[Sami, 2017/04/05 13:16:51]

Missing ')'

[altimin, 2017/04/05 13:55:18]

Done.

+    // work.
+    // Can be called on any thread
+    // All methods but SetObserver, SetTimeDomain and GetTimeDomain can be
+    // called on |queue|.
+    virtual void OnQueueNextWakeUpChanged(TaskQueue* queue,
+                                          base::TimeTicks next_wake_up) = 0;
+  };
+
   // Unregisters the task queue after which no tasks posted to it will run and
   // the TaskQueueManager's reference to it will be released soon.
   virtual void UnregisterTaskQueue() = 0;
@@ -150,7 +164,7 @@ class BLINK_PLATFORM_EXPORT TaskQueue : public base::SingleThreadTaskRunner {
   // NOTE: this must be called on the thread this TaskQueue was created by.
   virtual bool HasPendingImmediateWork() const = 0;
 
-  // Returns requested run time of next scheduled wakeup for a delayed task
+  // Returns requested run time of next scheduled wake_up for a delayed task

[Sami, 2017/04/05 13:16:52]

nit: no underscore

[altimin, 2017/04/05 13:55:18]

Done.

   // which is not ready to run. If there are no such tasks or the queue is
   // disabled (by a QueueEnabledVoter) it returns base::nullopt.
   // NOTE: this must be called on the thread this TaskQueue was created by.
@@ -208,6 +222,8 @@ class BLINK_PLATFORM_EXPORT TaskQueue : public base::SingleThreadTaskRunner {
 
   virtual bool BlockedByFence() const = 0;
 
+  virtual void SetObserver(Observer* observer) = 0;
+
  protected:
   ~TaskQueue() override {}