Revert 247993 "Media Galleries: Initial media scanner implementa..."

Brand-new test, MediaFolderFinderTest.ScanAndCancel, failed on Mac.

> Media Galleries: Initial media scanner implementation.
> 
> BUG=161119
> 
> Review URL: https://codereview.chromium.org/149363004

TBR=thestig@chromium.org

Review URL: https://codereview.chromium.org/134853003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248006 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248006
Expand the QuickTime quirk to handle all mime types used by that plugin.

BUG=308466
R=ananta@chromium.org

Review URL: https://codereview.chromium.org/150153002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@248007 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 248007