Reland update over cellular changes

This merge cherrypicks two commits that was reverted in an AOSP git merge.

4b0d6032cbb86ce488c03b31936cda31283f97e3 Add functions to allow update over cellular (including tethered connection)
840703a4cc77228e2606f45665ae3a4bd75ff7dd Fix update over cellular network on guest account

Handled multi-package response.

Ran clang-format which fixed a lot of issues in those two CLs.

BUG=chromium:815356
TEST=unittests, precq

Change-Id: I54b6763c4c54755272531b558ed7628ceb0fc6c7
Reviewed-on: https://chromium-review.googlesource.com/965267
Commit-Ready: Amin Hassani <ahassani@chromium.org>
Tested-by: Amin Hassani <ahassani@chromium.org>
Reviewed-by: Ben Chan <benchan@chromium.org>
diff --git a/mock_connection_manager.h b/mock_connection_manager.h
index e37460b..2fff68c 100644
--- a/mock_connection_manager.h
+++ b/mock_connection_manager.h
@@ -36,6 +36,7 @@
 
   MOCK_CONST_METHOD2(IsUpdateAllowedOver,
                      bool(ConnectionType type, ConnectionTethering tethering));
+  MOCK_CONST_METHOD0(IsAllowedConnectionTypesForUpdateSet, bool());
 };
 
 }  // namespace chromeos_update_engine