Add AudioLogFactory mojo interface.

This interface allows a mojo client to create audio logs on
the browser process.
This CL also removes content::MojoLogAudioAdapter, which is moved to the
audio service as audio::LogAdapter in follow-up CL crrev.com/c/1128974

Bug: 812557
Change-Id: I70504a4878553f1a3c2d58a29c6ab960b6f15b39
Reviewed-on: https://chromium-review.googlesource.com/1128966
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574508}
8 files changed