Autotest: fix for touch scrolling test flake.

For some reason, setting the scroll height via telemetry call sometimes
does not work.  Instead, have the starting scroll height be a feature of the
test page itself and reload the page.  In experiements, this method is not
flaky.

Also fix some logging issues.

BUG=None
TEST=looped scrollDirection 500 times on local machine and saw no flake; ran all
tests affected by this change.

Change-Id: I5f6e71292cacb72093b03163078af99852cfa3e2
Reviewed-on: https://chromium-review.googlesource.com/220372
Reviewed-by: Kalin Stoyanov <kalin@chromium.org>
Commit-Queue: Katherine Threlkeld <kathrelkeld@chromium.org>
Tested-by: Katherine Threlkeld <kathrelkeld@chromium.org>
5 files changed