Adds a pref for autoclick menu location within the screen.

The user will be able to move the autoclick menu around the
screen. This adds a preference to track the user's preferred
menu position, with a default in the lower right corner.

Bug: 943703
Change-Id: I2a2d147455971624dd396970264927567ce6029d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1531387
Commit-Queue: Katie Dektar <katie@chromium.org>
Reviewed-by: Dominick Ng <dominickn@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Reviewed-by: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#642773}
9 files changed