Add support library support for Override Proxy API

Static WebView methods are implemented using the class
WebViewFactoryProvider.Statics, in this CL we implement the
corresponding class for the WebView support library.

Bug: 851995
Change-Id: I2f9ed164d3b468acf77feaff4b0f192724ff511e
Reviewed-on: https://chromium-review.googlesource.com/1148384
Commit-Queue: Laís Minchillo <laisminchillo@chromium.org>
Reviewed-by: Bo <boliu@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581856}
13 files changed