make jitter_buffer_max_size available in blink layer under origin trial

link to the experiment thread
https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/hE2B1iItPDk

Bug: chromium:904764
Change-Id: Ic89e7915a21c60868e0a25b5a9ba160956f86c69
Reviewed-on: https://chromium-review.googlesource.com/c/1332194
Commit-Queue: Ruslan Burakov <kuddai@google.com>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#608752}
8 files changed