Most of these constructors are unused. Remove the unused ones,
and change the usage of existing constructors to be consistent.

BUG=angle:466,697

Change-Id: I455dd314036e1dfcb8c4690bab577b81dd0e060c
Reviewed-on: https://chromium-review.googlesource.com/208355Tested-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Nicolas Capens <capn@chromium.org>