Avoid unnecessary std::string allocations.

net/base/registry_controlled_domains/registry_controlled_domain.h

Index: net/base/registry_controlled_domains/registry_controlled_domain.h
diff --git a/net/base/registry_controlled_domains/registry_controlled_domain.h b/net/base/registry_controlled_domains/registry_controlled_domain.h
index 24ffb707a50ab5fd44e7b7f86427a9dfd0bff8b6..89aa6d6c18bc351d26a862a8f8fa79ef70aa325f 100644
--- a/net/base/registry_controlled_domains/registry_controlled_domain.h
+++ b/net/base/registry_controlled_domains/registry_controlled_domain.h
@@ -182,6 +182,14 @@ enum UnknownRegistryFilter {
 NET_EXPORT std::string GetDomainAndRegistry(const GURL& gurl,
                                             PrivateRegistryFilter filter);
 
+// Same as above, but returns the domain and registry as a StringPiece that
+// references the underlying string of the passed-in |gurl|.
+// TODO(pkalinnikov): Rename this to GetDomainAndRegistry and get rid of the
+// std::string-returning version. Update clients.
+NET_EXPORT base::StringPiece GetDomainAndRegistryAsStringPiece(
+    const GURL& gurl,
+    PrivateRegistryFilter filter);
+
 // Like the GURL version, but takes a host (which is canonicalized internally)
 // instead of a full GURL.
 NET_EXPORT std::string GetDomainAndRegistry(base::StringPiece host,