Remove webController from Tab

WebController is accessed from tab by BVC and preloadController to set
nativecontent and sideswipe delegates. Both are to be removed with
the release of slim navigation and the removal of native content.
For now create some utility methods to be used to set delegates inside
the webController of the webState and have them on the deprecated web
folder and use them instead of tab.

Bug: 960950
Change-Id: I79ba36b665e8fba92ec5595d5a51ec3ec6773de4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1674473
Commit-Queue: Mohammad Refaat <mrefaat@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#672562}
12 files changed