Revert "[Darwin][System] Ensure we do not delete the timer block context twic…" (project-chip#39750)

This reverts commit 2482755.

Author: woody-apple

src/platform/Darwin/system/SystemLayerImplDispatch.mm

@@ -60,6 +60,18 @@ static void TimerCompleteBlockCallback(Layer * aLayer, void * appState)
             if (ctx->block) {
                 ctx->block();
             }
+            delete ctx;
+        }
+
+        void MaybeCancelTimerCompleteBlockCallbackContext(TimerList::Node * timer)
+        {
+            VerifyOrReturn(nullptr != timer);
+
+            __auto_type & cb = timer->GetCallback();
+            VerifyOrReturn(cb.GetOnComplete() == TimerCompleteBlockCallback);
+
+            __auto_type * ctx = static_cast<TimerCompleteBlockCallbackContext *>(cb.GetAppState());
+            delete ctx;
         }
     }
 
@@ -109,6 +121,7 @@ static void TimerCompleteBlockCallback(Layer * aLayer, void * appState)
 
         TimerList::Node * timer;
         while ((timer = mTimerList.PopEarliest()) != nullptr) {
+            MaybeCancelTimerCompleteBlockCallbackContext(timer);
             DisableTimer(__func__, timer);
         }
         mTimerPool.ReleaseAll();
@@ -203,13 +216,6 @@ static void TimerCompleteBlockCallback(Layer * aLayer, void * appState)
                 mTimerPool.Invoke(timer);
             });
 
-            dispatch_source_set_cancel_handler(timerSource, ^{
-                VerifyOrReturn(onComplete == TimerCompleteBlockCallback);
-                VerifyOrReturn(nullptr != appState);
-
-                __auto_type * ctx = static_cast<TimerCompleteBlockCallbackContext *>(appState);
-                delete ctx; });
-
             EnableTimer(__func__, timer);
         }
 
@@ -280,6 +286,7 @@ static void TimerCompleteBlockCallback(Layer * aLayer, void * appState)
         }
         VerifyOrReturn(timer != nullptr);
 
+        MaybeCancelTimerCompleteBlockCallbackContext(timer);
         DisableTimer(__func__, timer);
 
         mTimerPool.Release(timer);
@@ -317,23 +324,8 @@ static void TimerCompleteBlockCallback(Layer * aLayer, void * appState)
         mExpiredTimers = mTimerList.ExtractEarlier(Clock::Timeout(1) + SystemClock().GetMonotonicTimestamp());
         TimerList::Node * timer = nullptr;
         while ((timer = mExpiredTimers.PopEarliest()) != nullptr) {
-            TimerCompleteBlockCallbackContext * context = nullptr;
-            bool shouldDeleteContext = false;
-
-            if (!HasTimerSource(timer)) {
-                __auto_type & cb = timer->GetCallback();
-                if (cb.GetOnComplete() == TimerCompleteBlockCallback) {
-                    context = static_cast<TimerCompleteBlockCallbackContext *>(cb.GetAppState());
-                    shouldDeleteContext = true;
-                }
-            }
-
             DisableTimer(__func__, timer);
             mTimerPool.Invoke(timer);
-
-            if (shouldDeleteContext) {
-                delete context;
-            }
         }
 #endif
     }