GitLab

We observed that users who need this feature get very confused and
lost when the mouse cursor goes into the magnifier viewport. This
CL makes it work as expected by confining the cursor outside the
viewport.

BUG=815208
TEST=Added test coverage

Change-Id: If93ea59a2d0cca7f48f9da47dd28dc395c25bc85
Reviewed-on: https://chromium-review.googlesource.com/940261Reviewed-by: kylechar <kylechar@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Commit-Queue: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#539999}