Eagerly remove disposed DOMTimers as observers upon completion.

third_party/WebKit/Source/core/frame/DOMTimerCoordinator.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 DOMTimerCoordinator_h
 #define DOMTimerCoordinator_h
 
 #include "platform/heap/Handle.h"
 #include "wtf/Noncopyable.h"
 #include "wtf/PassOwnPtr.h"
@@ skipping 14 matching lines @@
     DISALLOW_NEW();
     WTF_MAKE_NONCOPYABLE(DOMTimerCoordinator);
 public:
     explicit DOMTimerCoordinator(PassOwnPtr<WebTaskRunner>);
 
     // Creates and installs a new timer. Returns the assigned ID.
     int installNewTimeout(ExecutionContext*, ScheduledAction*, int timeout, bool singleShot);
 
     // Removes and disposes the timer with the specified ID, if any. This may
     // destroy the timer.
-    void removeTimeoutByID(int id);
+    DOMTimer* removeTimeoutByID(int id);
 
     // Timers created during the execution of other timers, and
     // repeating timers, are throttled. Timer nesting level tracks the
     // number of linked timers or repetitions of a timer. See
     // https://html.spec.whatwg.org/#timers
     int timerNestingLevel() { return m_timerNestingLevel; }
 
     // Sets the timer nesting level. Set when a timer executes so that
     // any timers created while the timer is executing will incur a
     // deeper timer nesting level, see DOMTimer::DOMTimer.
@@ skipping 12 matching lines @@
     TimeoutMap m_timers;
 
     int m_circularSequentialID;
     int m_timerNestingLevel;
     OwnPtr<WebTaskRunner> m_timerTaskRunner;
 };
 
 } // namespace blink
 
 #endif // DOMTimerCoordinator_h