Implement correct video story sound behaviour.

app/src/main/java/org/thoughtcrime/securesms/util/Debouncer.java

@@ -3,6 +3,8 @@ package org.thoughtcrime.securesms.util;
 import android.os.Handler;
 import android.os.Looper;
 
+import java.util.concurrent.TimeUnit;
+
 /**
  * A class that will throttle the number of runnables executed to be at most once every specified
  * interval. However, it could be longer if events are published consistently.
@@ -17,6 +19,10 @@ public class Debouncer {
   private final Handler handler;
   private final long    threshold;
 
+  public Debouncer(long threshold, TimeUnit timeUnit) {
+    this(timeUnit.toMillis(threshold));
+  }
+
   /**
    * @param threshold Only one runnable will be executed via {@link #publish(Runnable)} every
    *                  {@code threshold} milliseconds.