adjustments

library/core/src/main/java/com/google/android/exoplayer2/video/VideoFrameReleaseTimeHelper.java

@@ -44,10 +44,10 @@ public final class VideoFrameReleaseTimeHelper {
   private DisplayManager.DisplayListener displayListener = null;
   private Context context = null;
 
-  private VSyncSampler vsyncSampler;
-  private boolean useDefaultDisplayVsync;
-  private long vsyncDurationNs;
-  private long vsyncOffsetNs;
+  private VSyncSampler vsyncSampler = null;
+  private final boolean useDefaultDisplayVsync;
+  private long vsyncDurationNs = -1; // Value unused.
+  private long vsyncOffsetNs = -1; // Value unused.
 
   private long lastFramePresentationTimeUs;
   private long adjustedLastFrameTimeNs;
@@ -75,11 +75,10 @@ public final class VideoFrameReleaseTimeHelper {
   public VideoFrameReleaseTimeHelper(Context context) {
     this(getDefaultDisplayRefreshRate(context));
     this.context = context.getApplicationContext();
-    registerDisplayListener();
   }
 
   private VideoFrameReleaseTimeHelper(double defaultDisplayRefreshRate) {
-    setSync(defaultDisplayRefreshRate);
+    useDefaultDisplayVsync = defaultDisplayRefreshRate != DISPLAY_REFRESH_RATE_UNKNOWN;
   }
 
   /**
@@ -100,8 +99,8 @@ public final class VideoFrameReleaseTimeHelper {
   public void disable() {
     if (useDefaultDisplayVsync) {
       vsyncSampler.removeObserver();
+      unregisterDisplayListener();
     }
-    unregisterDisplayListener();
   }
 
   private void registerDisplayListener() {
@@ -128,15 +127,10 @@ public final class VideoFrameReleaseTimeHelper {
 
   private void setSync(double defaultDisplayRefreshRate) {
 
-    useDefaultDisplayVsync = defaultDisplayRefreshRate != DISPLAY_REFRESH_RATE_UNKNOWN;
     if (useDefaultDisplayVsync) {
       vsyncSampler = VSyncSampler.getInstance();
       vsyncDurationNs = (long) (C.NANOS_PER_SECOND / defaultDisplayRefreshRate);
       vsyncOffsetNs = (vsyncDurationNs * VSYNC_OFFSET_PERCENTAGE) / 100;
-    } else {
-      vsyncSampler = null;
-      vsyncDurationNs = -1; // Value unused.
-      vsyncOffsetNs = -1; // Value unused.
     }
   }