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

net/base/ip_endpoint_unittest.cc

Index: net/base/ip_endpoint_unittest.cc
diff --git a/net/base/ip_endpoint_unittest.cc b/net/base/ip_endpoint_unittest.cc
index 9f7c0f0b21b6c5222309d5666ce87750a90c6043..b3aa5b190dee5af5ad2130f94ca8266e00006f54 100644
--- a/net/base/ip_endpoint_unittest.cc
+++ b/net/base/ip_endpoint_unittest.cc
@@ -198,6 +198,12 @@ TEST_F(IPEndPointTest, ToString) {
     EXPECT_EQ(tests[index].host_normalized + ":" + base::UintToString(port),
               result);
   }
+
+  // ToString() shouldn't crash on invalid addresses.
+  IPAddress invalid_address;
+  IPEndPoint invalid_endpoint(invalid_address, 8080);
+  EXPECT_EQ("", invalid_endpoint.ToString());
+  EXPECT_EQ("", invalid_endpoint.ToStringWithoutPort());
 }
 
 }  // namespace