Fix bubble showing after dismiss bug.

Now we also show bubble in onCallListChange(), but we shouldn't show bubble after dismiss in this case.

Test: ReturnToCallControllerTest
PiperOrigin-RevId: 191101307
Change-Id: I13ff6bf4ae7ab574966c43c0e6fee13853899ba0
diff --git a/java/com/android/bubble/Bubble.java b/java/com/android/bubble/Bubble.java
index e192e06..1b853cf 100644
--- a/java/com/android/bubble/Bubble.java
+++ b/java/com/android/bubble/Bubble.java
@@ -39,6 +39,9 @@
   /** Returns whether the bubble is currently visible */
   boolean isVisible();
 
+  /** Returns whether the bubble is currently dismissed */
+  boolean isDismissed();
+
   /**
    * Set the info for this Bubble to display
    *