Fix incorrect dispatch of empty WindowInsets from ActionBarOverlayLayout

Fix a bug where ActionBarOverlayLayout was using a private constructor
of WindowInsets to return empty insets that should have been marked
fully consumed. This caused dispatch to further child views not to
stop appropriately, corrupting application layout in some cases.

Bug 15588587

Change-Id: I97fcefa4755addf2385a7e7b0ffbf6d3e91adc5c