Move CRWWebController.loadCancelled into CRWWKNavigationHandler.

This CL moves CRWWebController.loadCancelled into CRWWKNavigationHandler
and creates a new method in CRWWKNavigationHandlerDelegate to get
CRWWebController._isHalted.

Bug: 956511
Change-Id: Ib871d562351bca341a683b93735889e90322a5b2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1620643
Commit-Queue: Yi Su <mrsuyi@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662094}
3 files changed