media/gpu/VDA unittest: Save dump yuv files in .frames directory

VDA unittest saves dump yuv files in the directory whose path is exactly same as
the video file. It conflicts the video file and fails to create the directory.
As a result, it causes failures to save dump yuv files in the directory. This
fixes the issue by adding ".frames" suffix to the save directory.

Bug: None
Test: VDA test --frame_validator=dump
Change-Id: Id829ef219a91e82a071e506bae37939cc0c70dbd
Reviewed-on: https://chromium-review.googlesource.com/c/1477138
Commit-Queue: Hirokazu Honda <hiroh@chromium.org>
Reviewed-by: David Staessens <dstaessens@chromium.org>
Cr-Commit-Position: refs/heads/master@{#633183}
2 files changed