Fixing scrolling up in App Apps.

Done by scrolling only when scroll position is not zero. This way, the
scroll gesture can't close All Apps.

Bug: 110103162
Test: TaplTests suite
Change-Id: Icfe47d2bcc0210ae221df169d6c35cd1be10ff86

src/com/android/launcher3/Utilities.java

@@ -602,4 +602,8 @@ public final class Utilities {
         msg.setAsynchronous(true);
         handler.sendMessage(msg);
     }
+
+    public interface Consumer<T> {
+        void accept(T var1);
+    }
 }