Fire timer immediately if there is no tick_interval or targetTimestamp

Author: knopp

shell/platform/darwin/macos/framework/Source/FlutterVSyncWaiter.mm

@@ -104,28 +104,27 @@ - (void)waitForVSync:(uintptr_t)baton {
   TRACE_VSYNC("VSyncRequest", _pending_baton.value_or(0));
 
   CFTimeInterval tick_interval = _displayLink.nominalOutputRefreshPeriod;
-  NSLog(@">> TICK INTERVAL %f", tick_interval);
   if (_displayLink.paused || tick_interval == 0) {
     // When starting display link the first notification will come in the middle
     // of next frame, which would incur a whole frame period of latency.
     // To avoid that, first vsync notification will be fired using a timer
     // scheduled to fire where the next frame is expected to start.
     // Also use a timer if display link does not belong to any display
     // (nominalOutputRefreshPeriod being 0)
-    CFTimeInterval phase = fmod(_lastTargetTimestamp, tick_interval);
-    CFTimeInterval now = CACurrentMediaTime();
-    CFTimeInterval start = now - (fmod(now, tick_interval)) + phase;
-    if (start < now) {
-      start += tick_interval;
+    CFTimeInterval delay = 0;
+    if (tick_interval != 0 && _lastTargetTimestamp != 0) {
+      CFTimeInterval phase = fmod(_lastTargetTimestamp, tick_interval);
+      CFTimeInterval now = CACurrentMediaTime();
+      CFTimeInterval start = now - (fmod(now, tick_interval)) + phase;
+      if (start < now) {
+        start += tick_interval;
+      }
+      delay = start - now;
     }
-    CFTimeInterval delay = start - now;
-
-    NSLog(@"Scheduling timer in %f", delay);
 
     NSTimer* timer = [NSTimer timerWithTimeInterval:delay
                                             repeats:NO
                                               block:^(NSTimer* timer) {
-                                                NSLog(@"Firing synthesized vsync");
                                                 CFTimeInterval timestamp = CACurrentMediaTime();
                                                 CFTimeInterval targetTimestamp =
                                                     timestamp + tick_interval;