Revert of Resubmit enable the volume slider in Ash for windows. (https://codereview.chromium.org/193173002/)

Reason for revert:
Broke ash_unittests on Vista:
http://build.chromium.org/p/chromium.win/builders/Vista%20Tests%20%282%29/builds/41713/steps/ash_unittests/logs/AshTestHelper

Original issue's description:
> Resubmit enable the volume slider in Ash for windows.
> 
> BUG=227247
> 
> This is a resubmit of https://codereview.chromium.org/178883004/
> 
> That patch caused tests to fail on Vista due to uninitialized COM errors.  
> I've uploaded this patch as a diff to that codereview as well (Patch Set 11), so you can diff Patch Set 11 against Patch Set 10 to see the fix.
> 
> In words though, the fix is:
> 
> 1) Don't special-case DesktopNotificationsTest for COM initialization, instead fix AuraShellTestSuite to correctly initialize COM for Win7+, not just Win8+ (since Ash is supported on Win7).
> 
> 2) Make the same fix for Win7 in InProcessBrowserTest.
> 
> 3) In AshTestSuiteTest, don't run the test on Vista and below since Ash isn't supported prior to Win7 (I don't know of a better way to disable this test at runtime based on OS version).
> 
> TBR=henrika, jennyz
> R=sky
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=256374

TBR=sky@chromium.org,zturner@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=227247

Review URL: https://codereview.chromium.org/197513003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@256531 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 256531