Fix use of API level 19 method

Issue: #1965

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=136595233

library/src/main/java/com/google/android/exoplayer2/ui/PlaybackControlView.java

@@ -75,6 +75,7 @@ public class PlaybackControlView extends FrameLayout {
   private ExoPlayer player;
   private VisibilityListener visibilityListener;
 
+  private boolean isAttachedToWindow;
   private boolean dragging;
   private int rewindMs;
   private int fastForwardMs;
@@ -264,7 +265,7 @@ public class PlaybackControlView extends FrameLayout {
     removeCallbacks(hideAction);
     if (showTimeoutMs > 0) {
       hideAtMs = SystemClock.uptimeMillis() + showTimeoutMs;
-      if (isAttachedToWindow()) {
+      if (isAttachedToWindow) {
         postDelayed(hideAction, showTimeoutMs);
       }
     } else {
@@ -279,7 +280,7 @@ public class PlaybackControlView extends FrameLayout {
   }
 
   private void updatePlayPauseButton() {
-    if (!isVisible() || !isAttachedToWindow()) {
+    if (!isVisible() || !isAttachedToWindow) {
       return;
     }
     boolean playing = player != null && player.getPlayWhenReady();
@@ -291,7 +292,7 @@ public class PlaybackControlView extends FrameLayout {
   }
 
   private void updateNavigation() {
-    if (!isVisible() || !isAttachedToWindow()) {
+    if (!isVisible() || !isAttachedToWindow) {
       return;
     }
     Timeline currentTimeline = player != null ? player.getCurrentTimeline() : null;
@@ -315,7 +316,7 @@ public class PlaybackControlView extends FrameLayout {
   }
 
   private void updateProgress() {
-    if (!isVisible() || !isAttachedToWindow()) {
+    if (!isVisible() || !isAttachedToWindow) {
       return;
     }
     long duration = player == null ? 0 : player.getDuration();
@@ -426,6 +427,7 @@ public class PlaybackControlView extends FrameLayout {
   @Override
   public void onAttachedToWindow() {
     super.onAttachedToWindow();
+    isAttachedToWindow = true;
     if (hideAtMs != C.TIME_UNSET) {
       long delayMs = hideAtMs - SystemClock.uptimeMillis();
       if (delayMs <= 0) {
@@ -440,6 +442,7 @@ public class PlaybackControlView extends FrameLayout {
   @Override
   public void onDetachedFromWindow() {
     super.onDetachedFromWindow();
+    isAttachedToWindow = false;
     removeCallbacks(updateProgressAction);
     removeCallbacks(hideAction);
   }