GitLab

If there are more than 1 keep alive frames received before getting
the ack on request, the second will be thought as a continuation
fragment and fail with "Malformed Frame Continuation Fragment".

Change-Id: I69fb5c024f14fe19bfc60da2a2392b663bdcea66
Bug: 880053
Reviewed-on: https://chromium-review.googlesource.com/1237267
Commit-Queue: Yuankai Yu <yyk@google.com>
Reviewed-by: Jan Wilken Dörrie <jdoerrie@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593644}