[inspector] move part of protocol out of experiment

.. and bumped version to 1.3!

R=dgozman@chromium.org,pfeldman@chromium.org,caseq@chhromium.org,alph@chromium.org,yangguo@chromium.org

Bug: none
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I7ece84949fe6078c0777f95ddee1a17dc573c538
Reviewed-on: https://chromium-review.googlesource.com/783272
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Pavel Feldman <pfeldman@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Alexei Filippov <alph@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49597}