Retrying to update the Perf BSS expectations after rolling in VP9 dependencies.

Retrying to update the Perf BSS expectations after rolling in VP9 dependencies.
First attempt in https://codereview.chromium.org/701853003/ does not update Linux 64bit.

The WebRtc roll in VP9 dependency https://codereview.chromium.org/703443004/.
WebRtc submit: https://code.google.com/p/webrtc/source/detail?r=7588

"linux-release/sizes/chrome-bss/bss": {"reva": 302608, "revb": 302608, "type":
     "absolute", "better": "lower", "improve": 501584, "regress": 554384, "sha1": "63
     34ce61"},

BUG=424235
TBR=andrewhayden@chromium.org,tommi@chromium.org

Review URL: https://codereview.chromium.org/698313002

Cr-Commit-Position: refs/heads/master@{#302628}