Add FaviconManager to handle favicon js messages

This CL moves the handler method for favicon Js message from
CRWWebController into a new class FaviconManager.

Bug: 956516
Change-Id: I9a74d7c1d768f5031b0f26e6358bf2b9d2b5fea3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1667442
Commit-Queue: Yi Su <mrsuyi@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#670824}
6 files changed