Revert 212022 "The previous implementation is not correct, it de..."
> The previous implementation is not correct, it depended on the Fullscreen video class, but the PowerSaveBlocker could be used for embedding video or the use case which isn't related to the video at all.
>
> This patch adds new API to PowerSaveBlocker.
>
> BUG=247892
>
> Review URL: https://chromiumcodereview.appspot.com/
17175009
TBR=michaelbai@chromium.org
Review URL: https://codereview.chromium.org/
19659002
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@212092 0039d316-1c4b-4281-b951-d872f2087c98