Revert 234532 "Do not set the cache to valid when the device lis..."

It proves that this CL does not fix the problem.


> Do not set the cache to valid when the device list is empty.
> 
> In some cases, for example when the machine just wakes up from sleeping, the camera might not be ready for enumeration. This will fool Chrome that there is no device attaching to the machine, and fail all the getUserMedia call.
> 
> This patch fixes the problem by not setting the cache to be valid when the list is empty.
> 
> BUG=317673
> TEST=using pixel, open the camera using, apprtc.appspot.com, put down the lip, wait until the machine gets to sleep, then wake up and use apprtc.appspot.com. The camera should work, at least after refreshing.
> R=perkj@chromium.org
> 
> Review URL: https://codereview.chromium.org/66303011

TBR=xians@chromium.org

Review URL: https://codereview.chromium.org/71563002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@234814 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 234814