Do a forceLayout if pending insets is changed after relayout window

We might have a pending MSG_RESIZED_REPORT, but if it's executed after
relayoutWindow, mPendingInsets will already be the new value and it'll
not forceLayout. So we need to forceLayout here to make sure the measure
cache is cleared.

bug: 29391054

Change-Id: I73793b1427b89e75700369ec3b37053a6a732f0d