Execute actions in action schedule immediately.

Run next action immediately without using the handler when the requested
delay is zero. This ensures that no other code can run between these two
actions to improve deterministic test behaviour.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=170456852

testutils/src/main/java/com/google/android/exoplayer2/testutil/ActionSchedule.java

@@ -16,6 +16,7 @@
 package com.google.android.exoplayer2.testutil;
 
 import android.os.Handler;
+import android.os.Looper;
 import android.view.Surface;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.Player;
@@ -342,7 +343,11 @@ public final class ActionSchedule {
       this.trackSelector = trackSelector;
       this.surface = surface;
       this.mainHandler = mainHandler;
-      clock.postDelayed(mainHandler, this, delayMs);
+      if (delayMs == 0 && Looper.myLooper() == mainHandler.getLooper()) {
+        run();
+      } else {
+        clock.postDelayed(mainHandler, this, delayMs);
+      }
     }
 
     @Override