Add unit tests for NTLMv1 portable implementation

net/http/http_auth_handler_ntlm_portable.cc

Index: net/http/http_auth_handler_ntlm_portable.cc
diff --git a/net/http/http_auth_handler_ntlm_portable.cc b/net/http/http_auth_handler_ntlm_portable.cc
index bb65b308c05644250a3293be0e46ecd721376442..4f0204c249f72974899632c335719de7e71f74ed 100644
--- a/net/http/http_auth_handler_ntlm_portable.cc
+++ b/net/http/http_auth_handler_ntlm_portable.cc
@@ -365,11 +365,19 @@ static int ParseType2Msg(const void* in_buf, uint32_t in_len, Type2Msg* msg) {
   uint32_t offset = ReadUint32(cursor);  // get offset from in_buf
   msg->target_len = 0;
   msg->target = NULL;
-  // Check the offset / length combo is in range of the input buffer, including
-  // integer overflow checking.
-  if (offset + target_len > offset && offset + target_len <= in_len) {
-    msg->target_len = target_len;
-    msg->target = ((const uint8_t*)in_buf) + offset;
+
+  // Target length 0 is valid and indicates no target information.
+  if (target_len != 0) {
+    // Check the offset / length combo is in range of the input buffer,
+    // including integer overflow checking.
+    if (offset + target_len > offset && offset + target_len <= in_len) {
+      msg->target_len = target_len;
+      msg->target = ((const uint8_t*)in_buf) + offset;
+    } else {
+      // Reject a message with a non-zero target length that
+      // would cause an overflow.
+      return ERR_UNEXPECTED;
+    }
   }
 
   // read flags