Fix telemetry_gpu_test's GN build.

Fix telemetry_gpu_test's GN build.

https://codereview.chromium.org/1364103002 caused an accidental
regression due to an apparent bug in the handling of groups as data
dependencies in GN. Thanks to dpranke@ for side-by-side debugging. Work
around this.

BUG=536192
TBR=brettw@chromium.org

Committed: https://crrev.com/a40f71f3fc0ed46a7d0f00fa1bcb39529d5b71c9
Cr-Commit-Position: refs/heads/master@{#350960}

[Ken Russell (switch to Gerrit), 2015-09-25 23:56:43]

kbr@chromium.org changed reviewers:
+ brettw@chromium.org

[Ken Russell (switch to Gerrit), 2015-09-25 23:57:12]

Thanks to dpranke@ for debugging and coming up with this workaround. CQ'ing
TBR'd.

[Ken Russell (switch to Gerrit), 2015-09-25 23:57:15]

The CQ bit was checked by kbr@chromium.org

[commit-bot: I haz the power, 2015-09-25 23:58:07]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1369813003/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1369813003/1

[Dirk Pranke, 2015-09-26 00:04:44]

dpranke@chromium.org changed reviewers:
+ dpranke@chromium.org

[Dirk Pranke, 2015-09-26 00:04:45]

lgtm

[brettw, 2015-09-26 00:45:24]

lgtm

[commit-bot: I haz the power, 2015-09-26 00:50:06]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-09-26 00:50:46]

Patchset 1 (id:??) landed as
https://crrev.com/a40f71f3fc0ed46a7d0f00fa1bcb39529d5b71c9
Cr-Commit-Position: refs/heads/master@{#350960}