Update mediarecorder OWNERS

Change-Id: I09c9a01620d2c9667e1a80c68a367952b10b6042
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2020926
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Reviewed-by: Miguel Casas <mcasas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735433}

third_party/blink/renderer/modules/mediarecorder/OWNERS

-peter@chromium.org
 guidou@chromium.org
+handellm@google.com
+peter@chromium.org
 
 # Original (legacy) owner.
 emircan@chromium.org