Add additional method for setPageTransformer.

Add new method that allows to specify if setting PageTransformer should
also enable hardware type layers for the ViewPager pages.

Additionally, clarify the impact of the default behavior of setting
PageTransformer.

Bug: 29358872
Change-Id: I9e2b1ab6d1c319259c670b9e0a22b966849abd14
2 files changed