Remove HttpAuth::Scheme enum in favor of a string.

net/http/http_auth_handler.cc

Index: net/http/http_auth_handler.cc
diff --git a/net/http/http_auth_handler.cc b/net/http/http_auth_handler.cc
index ab809faefae1189d9a1cf8a5c2ae1bf8f1897ed6..6f7484c9d56f95e55f0822bede4bbccfa991d94a 100644
--- a/net/http/http_auth_handler.cc
+++ b/net/http/http_auth_handler.cc
@@ -7,13 +7,13 @@
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
+#include "base/string_util.h"
 #include "net/base/net_errors.h"
 
 namespace net {
 
 HttpAuthHandler::HttpAuthHandler()
-    : auth_scheme_(HttpAuth::AUTH_SCHEME_MAX),
-      score_(-1),
+    : score_(-1),
       target_(HttpAuth::AUTH_NONE),
       properties_(-1) {
 }
@@ -39,7 +39,8 @@ bool HttpAuthHandler::InitFromChallenge(
   // realm may be empty.
   DCHECK(!ok || score_ != -1);
   DCHECK(!ok || properties_ != -1);
-  DCHECK(!ok || auth_scheme_ != HttpAuth::AUTH_SCHEME_MAX);
+  DCHECK(!ok || (!auth_scheme_.empty() &&
+                 StringToLowerASCII(auth_scheme_) == auth_scheme_));
 
   return ok;
 }