Address PR feedback

Author: markushi

sentry-android-core/src/main/java/io/sentry/android/core/internal/util/SentryFrameMetricsCollector.java

@@ -14,13 +14,11 @@
 import android.view.Window;
 import androidx.annotation.RequiresApi;
 import io.sentry.ILogger;
-import io.sentry.ISentryLifecycleToken;
 import io.sentry.SentryLevel;
 import io.sentry.SentryOptions;
 import io.sentry.SentryUUID;
 import io.sentry.android.core.BuildInfoProvider;
 import io.sentry.android.core.ContextUtils;
-import io.sentry.util.AutoClosableReentrantLock;
 import io.sentry.util.Objects;
 import java.lang.ref.WeakReference;
 import java.lang.reflect.Field;
@@ -40,8 +38,7 @@ public final class SentryFrameMetricsCollector implements Application.ActivityLi
 
   private final @NotNull BuildInfoProvider buildInfoProvider;
   private final @NotNull Set<Window> trackedWindows = new CopyOnWriteArraySet<>();
-  private final @NotNull AutoClosableReentrantLock trackedWindowsLock =
-      new AutoClosableReentrantLock();
+
   private final @NotNull ILogger logger;
   private @Nullable Handler handler;
   private @Nullable WeakReference<Window> currentWindow;
@@ -292,11 +289,7 @@ private void stopTrackingWindow(final @NotNull Window window) {
               try {
                 // Re-check if we should still remove the listener for this window
                 // in case trackCurrentWindow was called in the meantime
-                final boolean shouldRemove;
-                try (final @NotNull ISentryLifecycleToken ignored = trackedWindowsLock.acquire()) {
-                  shouldRemove = trackedWindows.contains(window) && trackedWindows.remove(window);
-                }
-                if (shouldRemove) {
+                if (trackedWindows.remove(window)) {
                   windowFrameMetricsManager.removeOnFrameMetricsAvailableListener(
                       window, frameMetricsAvailableListener);
                 }
@@ -330,13 +323,7 @@ private void trackCurrentWindow() {
       new Handler(Looper.getMainLooper())
           .post(
               () -> {
-                // Re-check if we should still track this window
-                // in case stopTrackingWindow was called for the same Window in the meantime
-                final boolean shouldAdd;
-                try (final @NotNull ISentryLifecycleToken ignored = trackedWindowsLock.acquire()) {
-                  shouldAdd = !trackedWindows.contains(window) && trackedWindows.add(window);
-                }
-                if (shouldAdd) {
+                if (trackedWindows.add(window)) {
                   try {
                     windowFrameMetricsManager.addOnFrameMetricsAvailableListener(
                         window, frameMetricsAvailableListener, handler);
@@ -411,6 +398,9 @@ default void addOnFrameMetricsAvailableListener(
     default void removeOnFrameMetricsAvailableListener(
         final @NotNull Window window,
         final @Nullable Window.OnFrameMetricsAvailableListener frameMetricsAvailableListener) {
+      if (frameMetricsAvailableListener == null) {
+        return;
+      }
       window.removeOnFrameMetricsAvailableListener(frameMetricsAvailableListener);
     }
   }