Fix video_PlaybackPerf to work with performance dashboard.

Match the test name in upload data with the test name in the json
config file.
Change the result description presented in dashboard.

BUG=chromium:391396
TEST=test on peach_pit

Change-Id: I9f3ab0f31b081dae62249f57e6b93c04fa0ec9e3
Reviewed-on: https://chromium-review.googlesource.com/211983
Reviewed-by: Wu-Cheng Li <wuchengli@chromium.org>
Commit-Queue: Wen-Ding Li <wending@google.com>
Tested-by: Wen-Ding Li <wending@google.com>
4 files changed