Update MediaStreamDeviceObserver in renderer manifest

This interface was moved from content to blink in
crrev.com/622534, but we forgot to update the manifest.

Bug: 923190
Change-Id: Ib7a398ce6dfd967b361c18b39ca2b6961d1e2b20
Reviewed-on: https://chromium-review.googlesource.com/c/1419839
Reviewed-by: Kinuko Yasuda <kinuko@chromium.org>
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Cr-Commit-Position: refs/heads/master@{#624016}
1 file changed