I created a cl to disable the test.
https://codereview.chromium.org/2504113002

tommycli@
Could you please handle this?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/9bcbdb424425552223e7c589b81d4917ad9c1801

commit 9bcbdb424425552223e7c589b81d4917ad9c1801
Author: horo <horo@chromium.org>
Date: Wed Nov 16 06:28:44 2016

Disable PluginPowerSaverBrowserTest.BackgroundTabPlugins.

BUG= 665706 , 574266 
TBR=tommycli@chromium.org

Review-Url: https://codereview.chromium.org/2504113002
Cr-Commit-Position: refs/heads/master@{#432392}

[modify] https://crrev.com/9bcbdb424425552223e7c589b81d4917ad9c1801/chrome/browser/plugins/plugin_power_saver_browsertest.cc

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/229242e4a11140a623e694c80160ca3565755e73

commit 229242e4a11140a623e694c80160ca3565755e73
Author: tommycli <tommycli@chromium.org>
Date: Thu Nov 17 20:13:40 2016

Revert of Disable PluginPowerSaverBrowserTest.BackgroundTabPlugins (patchset #1 id:1 of https://codereview.chromium.org/2504113002/ )

Reason for revert:
Reverting this, because https://codereview.chromium.org/2504573003/ should have fixed the underlying issue. (Landed around the same time)

Original issue's description:
> Disable PluginPowerSaverBrowserTest.BackgroundTabPlugins.
>
> BUG= 665706 , 574266 
> TBR=tommycli@chromium.org
>
> Committed: https://crrev.com/9bcbdb424425552223e7c589b81d4917ad9c1801
> Cr-Commit-Position: refs/heads/master@{#432392}

TBR=horo@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG= 665706 , 574266 

Review-Url: https://codereview.chromium.org/2508713004
Cr-Commit-Position: refs/heads/master@{#432942}

[modify] https://crrev.com/229242e4a11140a623e694c80160ca3565755e73/chrome/browser/plugins/plugin_power_saver_browsertest.cc