Move mock_web_rtc_peer_connection_handler_client.cc|h to Blink

These files need to be moved to Blink as part of the phase 8 on
the design document [1].

[1] https://docs.google.com/document/d/1AJKVA5U4nDkyDB9p4ROrggWXadCxyy-grKaE9KS5vOU/edit?ts=5d5c1757

Since they can get moved independently, this CL does so, so reviewing
the main CL is eased.

BUG=787254
R=guidou@chromium.org, haraken@chromium.org

Change-Id: I23f65a6187f2eb1402170ebf182552d054ad3fdb
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1839091
Commit-Queue: Antonio Gomes <tonikitoo@igalia.com>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#705097}
8 files changed