buffet: Added unit tests for DeviceRegistrationInfo class

Added unit tests for GCD registration workflow in Buffet.

BUG=chromium:367381
TEST=Unit tests pass (old and new).

Change-Id: Ia3ad5f028ae6fc7f3d2acdf4648ceb88cc4e00ef
Reviewed-on: https://chromium-review.googlesource.com/197568
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Christopher Wiley <wiley@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
diff --git a/buffet/buffet.gyp b/buffet/buffet.gyp
index 2288162..c4c5a1b 100644
--- a/buffet/buffet.gyp
+++ b/buffet/buffet.gyp
@@ -76,6 +76,7 @@
         'async_event_sequencer_unittest.cc',
         'buffet_testrunner.cc',
         'data_encoding_unittest.cc',
+        'device_registration_info_unittest.cc',
         'exported_property_set_unittest.cc',
         'http_connection_fake.cc',
         'http_transport_fake.cc',