[Media Intent Handler] Add video/3gpp to supported MIME types

This fixes an issue where Chrome will only download a video/3gpp file
instead of playing it when opened with Chrome.

Bug: 910658, 923081
Change-Id: I0fcdfe5952f0020c35fe09a0db85a4e83fe4d37a
Reviewed-on: https://chromium-review.googlesource.com/c/1437720
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Chrome Cunningham <chcunningham@chromium.org>
Commit-Queue: Tommy Steimel <steimel@chromium.org>
Cr-Original-Commit-Position: refs/heads/master@{#626310}(cherry picked from commit 3b0ab072e430639b63131f14fe3d9c3986b915aa)
Reviewed-on: https://chromium-review.googlesource.com/c/1447253
Reviewed-by: Tommy Steimel <steimel@chromium.org>
Cr-Commit-Position: refs/branch-heads/3683@{#78}
Cr-Branched-From: e51029943e0a38dd794b73caaf6373d5496ae783-refs/heads/master@{#625896}
2 files changed