Add explicit TargetApi annotation to remove lint error

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=136597149

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

@@ -15,6 +15,7 @@
  */
  */
 package com.google.android.exoplayer2.ui;
 package com.google.android.exoplayer2.ui;
 
 
+import android.annotation.TargetApi;
 import android.content.Context;
 import android.content.Context;
 import android.content.res.TypedArray;
 import android.content.res.TypedArray;
 import android.os.SystemClock;
 import android.os.SystemClock;
@@ -351,13 +352,18 @@ public class PlaybackControlView extends FrameLayout {
   private void setButtonEnabled(boolean enabled, View view) {
   private void setButtonEnabled(boolean enabled, View view) {
     view.setEnabled(enabled);
     view.setEnabled(enabled);
     if (Util.SDK_INT >= 11) {
     if (Util.SDK_INT >= 11) {
-      view.setAlpha(enabled ? 1f : 0.3f);
+      setViewAlphaV11(view, enabled ? 1f : 0.3f);
       view.setVisibility(VISIBLE);
       view.setVisibility(VISIBLE);
     } else {
     } else {
       view.setVisibility(enabled ? VISIBLE : INVISIBLE);
       view.setVisibility(enabled ? VISIBLE : INVISIBLE);
     }
     }
   }
   }
 
 
+  @TargetApi(11)
+  private void setViewAlphaV11(View view, float alpha) {
+    view.setAlpha(alpha);
+  }
+
   private String stringForTime(long timeMs) {
   private String stringForTime(long timeMs) {
     if (timeMs == C.TIME_UNSET) {
     if (timeMs == C.TIME_UNSET) {
       timeMs = 0;
       timeMs = 0;