[ios] Use ActionSheetCoordinator in ClearBrowsingData

- Uses ActionSheetCoordinator instead of UIAlertController to help handle presenting the popover in non-compact devices.
- Adds title to avoid seemingly odd double "clear browsing data" button in non-compact devices.

Screenshots:  https://drive.google.com/open?id=1OjP2BL_TNf5W1L1lluI-8Q52x-nnzOAj
https://drive.google.com/open?id=1_QnxFfKE0r6VqwjNoPFPYnLPfB42nL6W

Change-Id: Iedac56cc0217567206630baed8feb32ea50ae2de
Reviewed-on: https://chromium-review.googlesource.com/1120850
Commit-Queue: Chris Lu <thegreenfrog@chromium.org>
Reviewed-by: Mark Cogan <marq@chromium.org>
Reviewed-by: Rohit Rao <rohitrao@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574636}
13 files changed