WebView Tools: use new devil Pull-as-root API

No change to production code, only a python script.

This uses the new `as_root` argument to device_utils.PullFile(). No
expected change to behavior, although this should be a slight
performance win for the script.

This depends on a catapult change (http://crrev.com/c/1580600).

Bug: 955233
Test: manual - script still works
Change-Id: I7ba2b6694378d6d186b5d595ef0c26818ed01a24
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1580597
Reviewed-by: Paul Miller <paulmiller@chromium.org>
Commit-Queue: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653891}
1 file changed