Add Mojo interface for Android screen capture

This is used to perform screen capture of the entire ChromeOS desktop
from Android applications via the MediaProjection API. This is just a
stub for the implementation in Chrome to keep the review size smaller.

Design doc is here: goto/arcppscreencapture

Bug: b:38452042
Change-Id: I91085b26c055ab2dce076ee143146e9978640ae3
Reviewed-on: https://chromium-review.googlesource.com/865798
Reviewed-by: Jorge Lucangeli Obes <[email protected]>
Reviewed-by: Luis Hector Chavez <[email protected]>
Commit-Queue: Jeffrey Kardatzke <[email protected]>
Cr-Commit-Position: refs/heads/master@{#530926}
12 files changed