Bug 1339588 - Part 1: Simplify nsTimerEvent::Cancel, since there's no need to release the nsTimerImpl itself. r=froydnj

MozReview-Commit-ID: 6br6DaDqxR0

--HG--
extra : rebase_source : 13cde860824483332c42ac2f86bca722bf42d36b
extra : source : 47a3ac382469cb8bd4cdfa123457a6d6b4f11d39

xpcom/threads/TimerThread.cpp

@@ -141,11 +141,7 @@ public:
 
   nsresult Cancel() override
   {
-    // Since nsTimerImpl is not thread-safe, we should release |mTimer|
+    mTimer->Cancel();
-    // here in the target thread to avoid race condition. Otherwise,
-    // ~nsTimerEvent() which calls nsTimerImpl::Release() could run in the
-    // timer thread and result in race condition.
-    mTimer = nullptr;
     return NS_OK;
   }
 
@@ -282,11 +278,6 @@ nsTimerEvent::GetName(nsACString& aName)
 NS_IMETHODIMP
 nsTimerEvent::Run()
 {
-  if (!mTimer) {
-    MOZ_ASSERT(false);
-    return NS_OK;
-  }
-
   if (MOZ_LOG_TEST(GetTimerLog(), LogLevel::Debug)) {
     TimeStamp now = TimeStamp::Now();
     MOZ_LOG(GetTimerLog(), LogLevel::Debug,
@@ -296,9 +287,7 @@ nsTimerEvent::Run()
 
   mTimer->Fire(mGeneration);
 
-  // We call Cancel() to correctly release mTimer.
+  return NS_OK;
-  // Read more in the Cancel() implementation.
-  return Cancel();
 }
 
 nsresult