GitLab

Now webrunner::FrameImpl creates WebContents and a WindowTreeHost.

Also moved FrameImpl and ContextImpl classes to //webrunner/browser
(because they run in the browser process).

Bug: 852145
Change-Id: Ic1f3e453342f182e28bbf971fae011a671bee105
Reviewed-on: https://chromium-review.googlesource.com/1135836Reviewed-by: Nico Weber <thakis@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Commit-Queue: Sergey Ulanov <sergeyu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575394}