Add missing #include around sequenced_worker_pool.h in //chrome

chrome/browser/supervised_user/supervised_user_url_filter.h

Index: chrome/browser/supervised_user/supervised_user_url_filter.h
diff --git a/chrome/browser/supervised_user/supervised_user_url_filter.h b/chrome/browser/supervised_user/supervised_user_url_filter.h
index 0b34d37f47912678b09440bfab1f78c60623197f..b1259f85b8e3940e31dc7f28235b419f8116fc62 100644
--- a/chrome/browser/supervised_user/supervised_user_url_filter.h
+++ b/chrome/browser/supervised_user/supervised_user_url_filter.h
@@ -25,12 +25,14 @@
 class GURL;
 class SupervisedUserBlacklist;
 
+namespace base {
+class TaskRunner;
+}
+
 namespace net {
 class URLRequestContextGetter;
 }
 
-class GURL;
-
 // This class manages the filtering behavior for a given URL, i.e. it tells
 // callers if a given URL should be allowed, blocked or warned about. It uses
 // information from multiple sources: