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- Create test utils
- Move the FormActivityTabHelper from WebStateObserver to Script callback
- Remove all the methods from WebState and WebStateObserver.

Bug: 823285
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I0953a91144524018dbff154b2ff5b7bd18e17013
Reviewed-on: https://chromium-review.googlesource.com/1133000
Commit-Queue: Olivier Robin <olivierrobin@chromium.org>
Reviewed-by: Moe Ahmadi <mahmadi@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#575630}