Remove obsolete includes of SigninManager

Bug: 798411
Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I0e178780249cda25b32dd521b3ed4288daca4650
Reviewed-on: https://chromium-review.googlesource.com/1127987
Reviewed-by: Olivier Robin <olivierrobin@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573258}
1 file changed