Continue the animation after the data is updated.

When the data is updated, the animation is interrupted because of the original
view is replaced by the new one from the new data. We should copy the original
animation and continue.

Handles the condition when the last photo is deleted.

Also some refinement of the codes.

bug:12196441
bug:12476802

Change-Id: I2139b09bf5f958af6fa21b91e3d0c14908e1ba79
diff --git a/src/com/android/camera/filmstrip/FilmstripContentPanel.java b/src/com/android/camera/filmstrip/FilmstripContentPanel.java
index 9a427fd..6db8f65 100644
--- a/src/com/android/camera/filmstrip/FilmstripContentPanel.java
+++ b/src/com/android/camera/filmstrip/FilmstripContentPanel.java
@@ -43,6 +43,13 @@
     /** Sets the listener. */
     void setFilmstripListener(FilmstripLayout.Listener listener);
 
+    /**
+     * Hides this panel with animation.
+     *
+     * @return {@code false} if already hidden.
+     */
+    boolean animateHide();
+
     /** Hides this panel */
     void hide();