Add empty view to avoid hamburger menu getting initial focus

Inspired by this: https://cs.corp.google.com/android/packages/apps/Contacts/res/layout/custom_action_bar.xml?dr&q=getting%5C+the%5C+initial%5C+focus&sq=file:%5Epackages/apps/Contacts/+package:%5Eandroid$&l=1

Bug 28074283
Bug 27687799

Change-Id: Ia7e7436f1e7e7ba3e7afd75596566e04ba971677