Fix flaky AsynchronousMediaCodecAdapterTest

The test was incorrectly assuming that with LooperMode.PAUSE,
HandlerThread instances needed explicit calls to execute
tasks. This commit fixes the test flakiness by manually pausing the
HandlerThead when needed.

PiperOrigin-RevId: 319411552

library/core/src/main/java/com/google/android/exoplayer2/mediacodec/AsynchronousMediaCodecAdapter.java

@@ -21,7 +21,6 @@ import android.media.MediaCrypto;
 import android.media.MediaFormat;
 import android.os.Handler;
 import android.os.HandlerThread;
-import android.os.Looper;
 import android.view.Surface;
 import androidx.annotation.GuardedBy;
 import androidx.annotation.IntDef;
@@ -251,19 +250,6 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     }
   }
 
-  @VisibleForTesting
-  /* package */ void onMediaCodecError(IllegalStateException e) {
-    synchronized (lock) {
-      mediaCodecAsyncCallback.onMediaCodecError(e);
-    }
-  }
-
-  @VisibleForTesting
-  @Nullable
-  /* package */ Looper getLooper() {
-    return handlerThread.getLooper();
-  }
-
   private void onFlushCompleted() {
     synchronized (lock) {
       onFlushCompletedSynchronized();