Refactor ClearSiteData to remove duplicate code

To simplify fixing Clear-Site-Data, I move some of the code that was
duplicated for the network_service into a shared location.

Bug: 898465
Change-Id: I25eac82e7a6f3481b03ac88946a1e7a6828cbfc9
Reviewed-on: https://chromium-review.googlesource.com/c/1350971
Commit-Queue: Christian Dullweber <[email protected]>
Reviewed-by: Martin Šrámek <[email protected]>
Cr-Commit-Position: refs/heads/master@{#611633}
5 files changed