Bug 1307350: Compensate for repeating timers that have not been appropriately cancelled. r=froydnj

MozReview-Commit-ID: 20VpLbgSjh4

--HG--
extra : rebase_source : b5b38c69c228b750e986cc502db1a6c2242919b4

xpcom/threads/TimerThread.cpp

@@ -570,6 +570,10 @@ TimerThread::AddTimer(nsTimerImpl* aTimer)
 {
   MonitorAutoLock lock(mMonitor);
 
+  if (!aTimer->mEventTarget) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
   // Add the timer to our list.
   int32_t i = AddTimerInternal(aTimer);
   if (i < 0) {
@@ -586,7 +590,7 @@ TimerThread::AddTimer(nsTimerImpl* aTimer)
 }
 
 nsresult
-TimerThread::RemoveTimer(nsTimerImpl* aTimer)
+TimerThread::RemoveTimer(nsTimerImpl* aTimer, bool aDisable)
 {
   MonitorAutoLock lock(mMonitor);
 
@@ -597,6 +601,10 @@ TimerThread::RemoveTimer(nsTimerImpl* aTimer)
     return NS_ERROR_NOT_AVAILABLE;
   }
 
+  if (aDisable) {
+    aTimer->mEventTarget = nullptr;
+  }
+
   // Awaken the timer thread.
   if (mWaiting) {
     mNotified = true;

xpcom/threads/TimerThread.h

@@ -44,7 +44,7 @@ public:
   nsresult Shutdown();
 
   nsresult AddTimer(nsTimerImpl* aTimer);
-  nsresult RemoveTimer(nsTimerImpl* aTimer);
+  nsresult RemoveTimer(nsTimerImpl* aTimer, bool aDisable=false);
 
   void DoBeforeSleep();
   void DoAfterSleep();

xpcom/threads/nsTimerImpl.cpp

@@ -326,17 +326,14 @@ void
 nsTimerImpl::Neuter()
 {
   if (gThread) {
-    gThread->RemoveTimer(this);
+    gThread->RemoveTimer(this, true);
   }
 
   // If invoked on the target thread, guarantees that the timer doesn't pop.
   // If invoked anywhere else, it might prevent the timer from popping, but
-  // no guarantees.
+  // no guarantees. In any case, the above RemoveTimer call will prevent it
+  // from being rescheduled.
   ++mGeneration;
-
-  // Breaks cycles when TimerEvents are in the queue of a thread that is no
-  // longer running.
-  mEventTarget = nullptr;
 }
 
 NS_IMETHODIMP