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In addition to the current functionality, this adds:
* Detection of default capture devices (communication and console).
* Detection of changes to the default communication render device.

While doing this, I decided to also make 'effects' visible in the media-internals page which was very helpful in tracking down the source of the problem I was running into.

BUG=347531

Review URL: https://codereview.chromium.org/187593004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255687 0039d316-1c4b-4281-b951-d872f2087c98