[ios] Fix uses of ios::ChromeBrowserState in /ios/chrome/browser/ui/webui

The ChromeBrowserState has been moved from the "ios" namespace
to the global namespace by http://crrev.com/c/2014913. Fix the
uses from ios::ChromeBrowserState to ChromeBrowserState.

Also remove includes of chrome_browser_state_forward.h and use
a simple forward declaration instead (since the old name is no
longer necessary).

This CL was uploaded by git cl split.

R=eugenebut@chromium.org

Bug: 1042208
Change-Id: Ic8e0433afeeabe0b65e8aed99c40b3a8ff513abe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2017426
Reviewed-by: Eugene But <eugenebut@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735294}
18 files changed