Make WebTaskRunner ThreadSafeRefCounted

third_party/WebKit/Source/core/workers/ParentFrameTaskRunners.h

 // Copyright 2016 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.
 
 #ifndef ParentFrameTaskRunners_h
 #define ParentFrameTaskRunners_h
 
 #include "core/CoreExport.h"
 #include "core/dom/ContextLifecycleObserver.h"
 #include "core/dom/TaskRunnerHelper.h"
@@ skipping 25 matching lines @@
   static ParentFrameTaskRunners* create(LocalFrame* frame) {
     return new ParentFrameTaskRunners(frame);
   }
 
   // Might return nullptr for unsupported task types.
   WebTaskRunner* get(TaskType);
 
   DECLARE_VIRTUAL_TRACE();
 
  private:
-  using TaskRunnerHashMap =
-      HashMap<TaskType, WebTaskRunner*, WTF::IntHash<TaskType>, TaskTypeTraits>;
+  using TaskRunnerHashMap = HashMap<TaskType,
+                                    RefPtr<WebTaskRunner>,
+                                    WTF::IntHash<TaskType>,
+                                    TaskTypeTraits>;
 
   // LocalFrame could be nullptr if the worker is not associated with a
   // particular local frame.
   explicit ParentFrameTaskRunners(LocalFrame*);
 
   void contextDestroyed() override;
 
   Mutex m_taskRunnersMutex;
   TaskRunnerHashMap m_taskRunners;
 };
 
 }  // namespace blink
 
 #endif  // ParentFrameTaskRunners_h