Make WebTaskRunner ThreadSafeRefCounted

third_party/WebKit/Source/platform/WebFrameScheduler.h

 // Copyright 2015 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 WebFrameScheduler_h
 #define WebFrameScheduler_h
 
+#include "wtf/RefPtr.h"
+
 namespace blink {
 
 class WebTaskRunner;
 class WebViewScheduler;
 
 class WebFrameScheduler {
  public:
   virtual ~WebFrameScheduler() {}
 
   // The scheduler may throttle tasks associated with offscreen frames.
   virtual void setFrameVisible(bool) {}
 
   // Tells the scheduler that the page this frame belongs to is not visible.
   // The scheduler may throttle tasks associated with pages that are not
   // visible.
   virtual void setPageVisible(bool) {}
 
   // Set whether this frame is suspended. Only unthrottledTaskRunner tasks are
   // allowed to run on a suspended frame.
   virtual void setSuspended(bool) {}
 
   // Set whether this frame is cross origin w.r.t. the top level frame. Cross
   // origin frames may use a different scheduling policy from same origin
   // frames.
   virtual void setCrossOrigin(bool) {}
 
   // Returns the WebTaskRunner for loading tasks.
   // WebFrameScheduler owns the returned WebTaskRunner.
-  virtual WebTaskRunner* loadingTaskRunner() { return nullptr; }
+  virtual RefPtr<WebTaskRunner> loadingTaskRunner() = 0;
 
   // Returns the WebTaskRunner for timer tasks.
   // WebFrameScheduler owns the returned WebTaskRunner.
-  virtual WebTaskRunner* timerTaskRunner() { return nullptr; }
+  virtual RefPtr<WebTaskRunner> timerTaskRunner() = 0;
 
   // Returns the WebTaskRunner for tasks which should never get throttled.
   // This is generally used for executing internal browser tasks which should
   // never be throttled. Ideally only tasks whose performance characteristics
   // are known should be posted to this task runner; for example user
   // JavaScript is discouraged. WebFrameScheduler owns the returned
   // WebTaskRunner.
-  virtual WebTaskRunner* unthrottledTaskRunner() { return nullptr; }
+  virtual RefPtr<WebTaskRunner> unthrottledTaskRunner() = 0;
 
   // Returns the parent WebViewScheduler.
   virtual WebViewScheduler* webViewScheduler() { return nullptr; }
 
   // Tells the scheduler a resource load has started. The scheduler may make
   // policy decisions based on this.
   virtual void didStartLoading(unsigned long identifier) {}
 
   // Tells the scheduler a resource load has stopped. The scheduler may make
   // policy decisions based on this.
   virtual void didStopLoading(unsigned long identifier) {}
 
   // Tells the scheduler if we are parsing a document on another thread. This
   // tells the scheduler not to advance virtual time if it's using the
   // DETERMINISTIC_LOADING policy.
   virtual void setDocumentParsingInBackground(bool) {}
 
   // Tells the scheduler that the first meaningful paint has occured for this
   // frame.
   virtual void onFirstMeaningfulPaint() {}
 };
 
 }  // namespace blink
 
 #endif  // WebFrameScheduler_h