Go back to previous state when hitting back from discovery bounce

Normally when you hit back, we just close the floating view if there
is one. This makes less sense for DiscoveryBounce, since it doesn't
feel like a different state even though it's technically a floating
view. So in that case, don't consume the back press; let launcher
handle it to go to the previous state.

Bug: 80075741
Change-Id: I7270b61be70509cb2101400a12929478a5d082aa

src/com/android/launcher3/AbstractFloatingView.java

@@ -121,9 +121,11 @@ public abstract class AbstractFloatingView extends LinearLayout implements Touch
 
     protected abstract boolean isOfType(@FloatingViewType int type);
 
-    public void onBackPressed() {
+    /** @return Whether the back is consumed. If false, Launcher will handle the back as well. */
+    public boolean onBackPressed() {
         logActionCommand(Action.Command.BACK);
         close(true);
+        return true;
     }
 
     @Override