Remove unnecessary #includes in background_contents_service.cc.

After the landing https://codereview.chromium.org/317203004,
background_contents_service.cc doesn't need the command line switch
related headers anymore. So we can remove these.

BUG=350898

Review URL: https://codereview.chromium.org/338083002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@277845 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/background/background_contents_service.cc

@@ -31,7 +31,6 @@
 #include "chrome/browser/ui/browser_finder.h"
 #include "chrome/browser/ui/browser_tabstrip.h"
 #include "chrome/browser/ui/host_desktop.h"
-#include "chrome/common/chrome_switches.h"
 #include "chrome/common/extensions/extension_constants.h"
 #include "chrome/common/pref_names.h"
 #include "content/public/browser/notification_service.h"