Scroll the hiding page to top on tab changed in sharesheet

After the tab changed, ResolverDrawerLayout will lose reference of the
hidden page which can cause the page not able to scoll back to top.
Automatically scroll on tab changed to avoid that situation.

Bug: 160886554
Test: manually test; atest ChooserActivityTest; atest
ResolverActivityTest

Change-Id: I1a8ba72f6b1dcb9bca19262b97983788001d715b
2 files changed