[Tango->FCM] Distinguish between known and unknown invaidation versions.

Currently we count all received invalidations in order to compare new
and deprecated invalidations implementation.
This doesn't work well, since in the deprecated implementation
invalidations with unknown versions are emited by the server.

This CL distinguish between cases when invalidation has known or unknown
version.

Bug: 801985
Change-Id: I2a46a59c253d149932deee7e52e96379b509f718
Reviewed-on: https://chromium-review.googlesource.com/c/1400834
Commit-Queue: Tatiana Gornak <melandory@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Reviewed-by: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621542}
2 files changed