[autotest] Add cursor centering to touch_MouseScroll
In order to fix existing flake, move the cursor to the center of the page
before continuing the scroll test.
Also adds a blocking playback function which calculates the length of a given
playback file and sleeps until the playback has completed.
TEST=Ran on several systems
BUG=None
Change-Id: I855e6075414e332301826d94e45f090ea49cd99b
Reviewed-on: https://chromium-review.googlesource.com/264441
Reviewed-by: Mussa Kiroga <mussa@chromium.org>
Commit-Queue: Katherine Threlkeld <kathrelkeld@chromium.org>
Tested-by: Katherine Threlkeld <kathrelkeld@chromium.org>
3 files changed