MediaRecorderHandler: connecting Blink factory method to content/

MediaRecorderHandler changes to implementing WebMediaRecorderHandler;

content/ overrides Blink's createMediaRecorderHandler().

context: MediaRecorderHandler is the Blink-orchestrated class
implementing MediaStream Recorder API (see below). It plugs
together an existing MediaStreamVideoTrack to a new
VideoTrackRecorder-WebmMuxer pair. When MSVTrack passes
frames, these get encoded, muxed, and the result is sent to
Blink. See DD @ (*) for the plan. The
previous CL landed
MediaRecorderHandler, this one allows for its activation.

(*) Used to be

Depends on to disable
Blink tests, that after landing-rolling, should be updated and


Review URL:

Cr-Commit-Position: refs/heads/master@{#348338}
6 files changed