Add histograms to collect handshake status when connection migration is triggered based on migration cause.

Bug: 790547
Change-Id: I08efdc45b558d711b310aac55f412381efc3eaa6
Reviewed-on: https://chromium-review.googlesource.com/1140532
Reviewed-by: Ryan Hamilton <rch@chromium.org>
Reviewed-by: Alexei Svitkine <asvitkine@chromium.org>
Commit-Queue: Zhongyi Shi <zhongyi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#576205}
2 files changed