Use Diplay.getMetrics in DisplayController

- This is a workaround of b/163815566, where DisplayMetrics is stale
  when onDisplayChanged is called.
- Instead of relying on stale DisplayConext, get the DisplayMetrics
  from the Display directly.
- Also optimized how DisplayController.Info is created by passing in
  Display only
- Use mDisplayContext.getDisplay directly if availalbe

Bug: 163815566, 160544577
Test: DPI looks correct on device boot
Change-Id: I2a7454bb8cf2073ce592e8662781b87fc998444f
(cherry picked from commit 177c38243dc3bf245d1f7db3c265dfb56522f441)