Move CRWWebController._navigationStates into CRWWKNavigationHandler.

This CL is a prerequiste work for extracting navigation related code
out of CRWWebController.

Bug: 956522
Change-Id: I1e365b11fa58b87e0710c70ae49d57984c83b0c7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1596569
Commit-Queue: Yi Su <mrsuyi@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#656965}
3 files changed