[ChromeDriver] Implementation of Set Window Rect

Will have a follow up CL with integration tests once both this and
Get Window Rect have been merged to master

Bug: chromedriver:1940
Change-Id: I07372f234028d4448d973adba29602f6e398cbee
Reviewed-on: https://chromium-review.googlesource.com/687154
Reviewed-by: John Chen <johnchen@chromium.org>
Commit-Queue: Jonathon Kereliuk <kereliuk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#510865}
7 files changed