[ios] Fix WebStateUserData to match the content implementation.

The content implementation was updated to work properly across
components. See https://chromium-review.googlesource.com/c/1354402.

[email protected]

Bug: 589840
Change-Id: Ie3fd2292c4c730e8e9db0516ea1b1c3899bc6909
Reviewed-on: https://chromium-review.googlesource.com/c/1476055
Commit-Queue: François Doray <[email protected]>
Reviewed-by: Eugene But <[email protected]>
Cr-Commit-Position: refs/heads/master@{#633743}
103 files changed