Abstract out surface between ScreenshotController and ScreenshotView

Building block for allowing us to rewrite the screenshot UI under a
flag.

Bug: 329659738
Flag: NONE
Test: atest, manual

Change-Id: Ib5dceefeda21e24c7eccf68cf9f44a154ae95f90
Merged-In: Ib5dceefeda21e24c7eccf68cf9f44a154ae95f90
6 files changed