Use the public type to compute the bar content frame

We won't have the internal insets type. And there might be multiple
status bars or navigation bars in the future. The CL refines the logic
about computing the content frame of the bar. Also, we don't assume
status bar is at the top of the display.

Bug: 234093736
Test: atest SizeCompatTests
Change-Id: I63ae873a86a01dbd6e63b0084bcfa425e84b3753