Issue #4692 - Move responsibility for engine reference from tasks to scheduler

include/AdblockPlus/JsEngine.h

Index: include/AdblockPlus/JsEngine.h
===================================================================
--- a/include/AdblockPlus/JsEngine.h
+++ b/include/AdblockPlus/JsEngine.h
@@ -74,9 +74,6 @@
    */
   typedef std::shared_ptr<ScopedV8Isolate> ScopedV8IsolatePtr;
 
-  struct ImmediateSingleUseThreadType {}; ///< Marker class for scheduling policy
-  extern const ImmediateSingleUseThreadType ImmediateSingleUseThread; ///< Dummy constant for scheduling policy
-
   /**
    * JavaScript engine used by `FilterEngine`, wraps v8.
    */
@@ -134,25 +131,6 @@
         const std::string& filename = "");
 
     /**
-     * Schedule a task with these policies:
-     * - timing policy: start execution immediately.
-     * - threading policy: run the task in a single-use thread.
-     *
-     * @param task
-     *   Task to execute. All v8 handles should refer to the present engine.
-     * @param ImmediateSingleUseThreadType
-     *   The schedule policy--create a new thread and discard it afterwards.
-     */
-    void Schedule(std::function<void()> task, ImmediateSingleUseThreadType);
-
-    /**
-     * Block until there are no more tasks running in the scheduler.
-     *
-     * Note: this function does not prevent new tasks from being scheduled.
-     */
-    void WaitForQuietScheduler();
-
-    /**
      * Initiates a garbage collection.
      */
     void Gc();
@@ -289,16 +267,6 @@
     WebRequestPtr webRequest;
     LogSystemPtr logSystem;
     EventMap eventCallbacks;
-
-    // Forward declaration for PImpl idiom
-    class SchedulerImpl;
-    /**
-     * Scheduler for tasks executed under the current engine.
-     *
-     * \par Invariant
-     *   `bool(scheduler)` is always true
-     */
-    std::unique_ptr<SchedulerImpl> scheduler;
   };
 }