UnifiedDesktop: mouse warp support

* Refactor utility functions in ExtendedMouseWarpController into display_util.h so that they can be used in both extended and unified mode.

* Move enable flag to MouseWarpControoler.
* Add UnifiedMouseWarpController, which uses MirrorDisplays's window and gfx::Display instead.
  - Added support methods in MirrorWindowController.

BUG=365662
TEST=UnifiedMouseWarpControllerTest

Review URL: https://codereview.chromium.org/1114633002

Cr-Commit-Position: refs/heads/master@{#327671}
21 files changed