Create a pure virtual interface for SafeBrowsingService.

The interface is currently minimal, only controlling the factory
function for SafeBrowsingServices. Over time I will port
non-SafeBrowsing code to use this interface, solving our cyclic
dependency problems.

Bug: 925153
Change-Id: I56184ddac8d279abd4b930922e7bedeb99ee7f56
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1490449
Commit-Queue: Daniel Rubery <[email protected]>
Reviewed-by: Lei Zhang <[email protected]>
Reviewed-by: Christian Dullweber <[email protected]>
Reviewed-by: Min Qin <[email protected]>
Reviewed-by: Varun Khaneja <[email protected]>
Cr-Commit-Position: refs/heads/master@{#658228}
12 files changed