Minor clean-up

Author: knopp

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

@@ -13,7 +13,6 @@ @interface FlutterDisplayLink () {
   _FlutterDisplayLinkView* _view;
   std::optional<CGDirectDisplayID> _display_id;
   void (^_block)(CFTimeInterval timestamp, CFTimeInterval targetTimestamp);
-
   BOOL _paused;
 }
 
@@ -60,10 +59,11 @@ bool ShouldBeRunning() {
   std::mutex mutex_;
 };
 
-void RunOrStopDisplayLink(CVDisplayLinkRef display_link, bool should_run) {
-  if (should_run) {
+void RunOrStopDisplayLink(CVDisplayLinkRef display_link, bool should_be_running) {
+  bool is_running = CVDisplayLinkIsRunning(display_link);
+  if (should_be_running && !is_running) {
     CVDisplayLinkStart(display_link);
-  } else {
+  } else if (!should_be_running && is_running) {
     CVDisplayLinkStop(display_link);
   }
 }
@@ -84,10 +84,10 @@ void RunOrStopDisplayLink(CVDisplayLinkRef display_link, bool should_run) {
         CVDisplayLinkRelease(display_link);
       } else {
         // Update the display link state outside of the mutex.
-        bool running = entry->ShouldBeRunning();
+        bool should_be_running = entry->ShouldBeRunning();
         CVDisplayLinkRef display_link = CVDisplayLinkRetain(entry->display_link_locked);
         lock.unlock();
-        RunOrStopDisplayLink(display_link, running);
+        RunOrStopDisplayLink(display_link, should_be_running);
         CVDisplayLinkRelease(display_link);
       }
       return;
@@ -101,10 +101,10 @@ void RunOrStopDisplayLink(CVDisplayLinkRef display_link, bool should_run) {
   for (ScreenEntry& entry : entries_) {
     if (entry.display_id == display_id) {
       entry.clients.push_back(displayLink);
-      bool running = entry.ShouldBeRunning();
+      bool should_be_running = entry.ShouldBeRunning();
       CVDisplayLinkRef display_link = CVDisplayLinkRetain(entry.display_link_locked);
       lock.unlock();
-      RunOrStopDisplayLink(display_link, running);
+      RunOrStopDisplayLink(display_link, should_be_running);
       CVDisplayLinkRelease(display_link);
       return;
     }
@@ -124,8 +124,8 @@ void RunOrStopDisplayLink(CVDisplayLinkRef display_link, bool should_run) {
       });
 
   // This is a new display link so it is safe to start it with mutex held.
-  bool running = entry.ShouldBeRunning();
-  RunOrStopDisplayLink(entry.display_link_locked, running);
+  bool should_be_running = entry.ShouldBeRunning();
+  RunOrStopDisplayLink(entry.display_link_locked, should_be_running);
   entries_.push_back(entry);
 }