We can use Seek + Advance instead on source stream.

TBR=verwaest@chromium.org

Bug: chromium:879550
Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ic6ad12a86105ce68ea404e313b74d11417928cf0
Reviewed-on: https://chromium-review.googlesource.com/1196686
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55552}