Revert of Reduce buggy usage of the registry controlled domain service.

components/url_formatter/url_fixer.cc

Index: components/url_formatter/url_fixer.cc
diff --git a/components/url_formatter/url_fixer.cc b/components/url_formatter/url_fixer.cc
index 4335b3955de9b903f858dd5cd11e411f7d21ff4f..c49b31ba08cb4ee680a9498c64abbd69c728f9d6 100644
--- a/components/url_formatter/url_fixer.cc
+++ b/components/url_formatter/url_fixer.cc
@@ -201,15 +201,20 @@
   if (desired_tld.empty() || domain->empty())
     return;
 
-  // Abort if we already have a known TLD. In the case of an invalid host,
-  // HostHasRegistryControlledDomain will return false and we will try to
-  // append a TLD (which may make it valid). For example, "999999999999" is
-  // detected as a broken IP address and marked invalid, but attaching ".com"
-  // makes it legal.  We disallow unknown registries here so users can input
-  // "mail.yahoo" and hit ctrl-enter to get "www.mail.yahoo.com".
-  if (net::registry_controlled_domains::HostHasRegistryControlledDomain(
+  // Check the TLD.  If the return value is positive, we already have a TLD, so
+  // abort.  If the return value is std::string::npos, there's no valid host,
+  // but we can try to append a TLD anyway, since the host may become valid once
+  // the TLD is attached -- for example, "999999999999" is detected as a broken
+  // IP address and marked invalid, but attaching ".com" makes it legal.  When
+  // the return value is 0, there's a valid host with no known TLD, so we can
+  // definitely append the user's TLD.  We disallow unknown registries here so
+  // users can input "mail.yahoo" and hit ctrl-enter to get
+  // "www.mail.yahoo.com".
+  const size_t registry_length =
+      net::registry_controlled_domains::GetRegistryLength(
           *domain, net::registry_controlled_domains::EXCLUDE_UNKNOWN_REGISTRIES,
-          net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES))
+          net::registry_controlled_domains::EXCLUDE_PRIVATE_REGISTRIES);
+  if ((registry_length != 0) && (registry_length != std::string::npos))
     return;
 
   // Add the suffix at the end of the domain.