Reland "Add browser test and testing config for dynamic Expect-CT reporting"

This is a reland of f51e5d491800e1a112f009266589625b1f6a4ab6
Original change's description:
> Add browser test and testing config for dynamic Expect-CT reporting
> 
> This CL adds a browser test to check that the ChromeExpectCTReporter is properly
> created and set up to receive reports, particularly for dynamic Expect-CT
> violations. It also enables the dynamic Expect-CT feature on the waterfall.
> 
> BUG=679012,642517
> 
> Change-Id: I3ea01207ea5852b9bd0bbb1d90799ee4555c854e
> Reviewed-on: https://chromium-review.googlesource.com/566572
> Reviewed-by: Jesse Doherty <jwd@chromium.org>
> Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
> Commit-Queue: Emily Stark <estark@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#486158}

TBR=jwd@chromium.org

Bug: 679012, 642517
Change-Id: If0a05ea0823f0427f04c455206ab8a7f7020fc89
Reviewed-on: https://chromium-review.googlesource.com/570561
Reviewed-by: Emily Stark <estark@chromium.org>
Reviewed-by: Mustafa Emre Acer <meacer@chromium.org>
Commit-Queue: Emily Stark <estark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#486637}
3 files changed