APM move: Move EchoInformation into media/webrtc

It will be used both by content::MediaStreamAudioProcessor and the
upcoming media::AudioProcessor.

For an outline of the project this CL is part of, see: https://docs.google.com/document/d/1u4POff_ts_1LE3WDLA_wDDFnUswdlsuHL5DsiTE0a3U/edit?usp=sharing
It's accessible to everyone @chromium.org.

Bug: 851959
Change-Id: I794558e46ab01fd2f367e1df2fababdefb712c4f
Reviewed-on: https://chromium-review.googlesource.com/1170841
Commit-Queue: Oskar Sundbom <ossu@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#583653}
9 files changed