[macOS] Set the display refresh rate (flutter#21095)

Fixes: flutter#49222

Author: iskakaushik

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

@@ -281,6 +281,7 @@ - (BOOL)runWithEntrypoint:(NSString*)entrypoint {
 
   [self sendUserLocales];
   [self updateWindowMetrics];
+  [self updateDisplayConfig];
   return YES;
 }
 
@@ -317,6 +318,31 @@ - (NSOpenGLContext*)resourceContext {
   return _resourceContext;
 }
 
+- (void)updateDisplayConfig {
+  if (!_engine) {
+    return;
+  }
+
+  CVDisplayLinkRef displayLinkRef;
+  CGDirectDisplayID mainDisplayID = CGMainDisplayID();
+  CVDisplayLinkCreateWithCGDisplay(mainDisplayID, &displayLinkRef);
+  CVTime nominal = CVDisplayLinkGetNominalOutputVideoRefreshPeriod(displayLinkRef);
+  if (!(nominal.flags & kCVTimeIsIndefinite)) {
+    double refreshRate = static_cast<double>(nominal.timeScale) / nominal.timeValue;
+
+    FlutterEngineDisplay display;
+    display.struct_size = sizeof(display);
+    display.display_id = mainDisplayID;
+    display.refresh_rate = round(refreshRate);
+
+    std::vector<FlutterEngineDisplay> displays = {display};
+    FlutterEngineNotifyDisplayUpdate(_engine, kFlutterEngineDisplaysUpdateTypeStartup,
+                                     displays.data(), displays.size());
+  }
+
+  CVDisplayLinkRelease(displayLinkRef);
+}
+
 - (void)updateWindowMetrics {
   if (!_engine) {
     return;