IPEndPoint::ToString should not crash when the IP address is empty.

net/base/ip_endpoint.h

Index: net/base/ip_endpoint.h
diff --git a/net/base/ip_endpoint.h b/net/base/ip_endpoint.h
index c2639b161d6f41dac152be0e7007afb484c5d4c9..c1facda7bbe0c47a11865472a752fa64d24b22d4 100644
--- a/net/base/ip_endpoint.h
+++ b/net/base/ip_endpoint.h
@@ -53,9 +53,8 @@ class NET_EXPORT IPEndPoint {
   bool FromSockAddr(const struct sockaddr* address, socklen_t address_length)
       WARN_UNUSED_RESULT;
 
-  // Returns value as a string (e.g. "127.0.0.1:80"). Returns empty
-  // string if the address is invalid, and cannot not be converted to a
-  // string.
+  // Returns value as a string (e.g. "127.0.0.1:80"). The IP address must be
+  // valid.
   std::string ToString() const;
 
   // As above, but without port.