Add missing (and remove superfluous) 'explicit' from constructors.

chrome/browser/net/pref_proxy_config_tracker_impl.h

Index: chrome/browser/net/pref_proxy_config_tracker_impl.h
diff --git a/chrome/browser/net/pref_proxy_config_tracker_impl.h b/chrome/browser/net/pref_proxy_config_tracker_impl.h
index d37c01c732e2c469ee98c4032af15438129a0bab..45a5b3da24e7d7384d385554fe5ce281368b915f 100644
--- a/chrome/browser/net/pref_proxy_config_tracker_impl.h
+++ b/chrome/browser/net/pref_proxy_config_tracker_impl.h
@@ -30,8 +30,8 @@ class ChromeProxyConfigService
   // Takes ownership of the passed |base_service|.
   // If |wait_for_first_update| is true, GetLatestProxyConfig returns
   // ConfigAvailability::CONFIG_PENDING until UpdateProxyConfig has been called.
-  explicit ChromeProxyConfigService(net::ProxyConfigService* base_service,
-                                    bool wait_for_first_update);
+  ChromeProxyConfigService(net::ProxyConfigService* base_service,
+                           bool wait_for_first_update);
   virtual ~ChromeProxyConfigService();
 
   // ProxyConfigService implementation: