Revert of Make IP Address related functions return the empty string when used on an invalid address.

net/base/ip_address_number.h

Index: net/base/ip_address_number.h
diff --git a/net/base/ip_address_number.h b/net/base/ip_address_number.h
index 4434fa05352053c4ffe9cc5ed17d569e02f008af..2671a24d653d5fd1b1a75958a304433fde2e4046 100644
--- a/net/base/ip_address_number.h
+++ b/net/base/ip_address_number.h
@@ -37,14 +37,12 @@
 NET_EXPORT bool IsIPAddressReserved(const IPAddressNumber& address);
 
 // Returns the string representation of an IP address.
-// For example: "192.168.0.1" or "::1". Returns the empty string when |address|
-// is invalid.
+// For example: "192.168.0.1" or "::1".
 NET_EXPORT std::string IPAddressToString(const uint8_t* address,
                                          size_t address_len);
 
 // Returns the string representation of an IP address along with its port.
-// For example: "192.168.0.1:99" or "[::1]:80". Returns the empty string when
-// |address| is invalid (the port will be ignored).
+// For example: "192.168.0.1:99" or "[::1]:80".
 NET_EXPORT std::string IPAddressToStringWithPort(const uint8_t* address,
                                                  size_t address_len,
                                                  uint16_t port);