Cleanup: Use AUTH_SCHEME enum instead of a string.

net/http/http_auth_cache.h

Index: net/http/http_auth_cache.h
===================================================================
--- net/http/http_auth_cache.h	(revision 71164)
+++ net/http/http_auth_cache.h	(working copy)
@@ -13,6 +13,7 @@
 #include "base/ref_counted.h"
 #include "base/string16.h"
 #include "googleurl/src/gurl.h"
+#include "net/http/http_auth.h"
 
 namespace net {
 
@@ -42,10 +43,11 @@
   // scheme |scheme|.
   //   |origin| - the {scheme, host, port} of the server.
   //   |realm|  - case sensitive realm string.
-  //   |scheme| - case sensitive authentication scheme, should be lower-case.
+  //   |scheme| - the authentication scheme (i.e. basic, negotiate).
   //   returns  - the matched entry or NULL.
-  Entry* Lookup(const GURL& origin, const std::string& realm,
-                const std::string& scheme);
+  Entry* Lookup(const GURL& origin,
+                const std::string& realm,
+                HttpAuth::Scheme scheme);
 
   // Find the entry on server |origin| whose protection space includes
   // |path|. This uses the assumption in RFC 2617 section 2 that deeper
@@ -62,7 +64,7 @@
   // paths list.
   //   |origin|   - the {scheme, host, port} of the server.
   //   |realm|    - the auth realm for the challenge.
-  //   |scheme|   - the authentication scheme for the challenge.
+  //   |scheme|   - the authentication scheme (i.e. basic, negotiate).
   //   |username| - login information for the realm.
   //   |password| - login information for the realm.
   //   |path|     - absolute path for a resource contained in the protection
@@ -70,7 +72,7 @@
   //   returns    - the entry that was just added/updated.
   Entry* Add(const GURL& origin,
              const std::string& realm,
-             const std::string& scheme,
+             HttpAuth::Scheme scheme,
              const std::string& auth_challenge,
              const string16& username,
              const string16& password,
@@ -80,13 +82,13 @@
   // if one exists AND if the cached identity matches (|username|, |password|).
   //   |origin|   - the {scheme, host, port} of the server.
   //   |realm|    - case sensitive realm string.
-  //   |scheme|   - authentication scheme
+  //   |scheme|   - the authentication scheme (i.e. basic, negotiate).
   //   |username| - condition to match.
   //   |password| - condition to match.
   //   returns    - true if an entry was removed.
   bool Remove(const GURL& origin,
               const std::string& realm,
-              const std::string& scheme,
+              HttpAuth::Scheme scheme,
               const string16& username,
               const string16& password);
 
@@ -97,7 +99,7 @@
   // cache, false otherwise.
   bool UpdateStaleChallenge(const GURL& origin,
                             const std::string& realm,
-                            const std::string& scheme,
+                            HttpAuth::Scheme scheme,
                             const std::string& auth_challenge);
 
  private:
@@ -119,8 +121,8 @@
     return realm_;
   }
 
-  // The authentication scheme string of the challenge
-  const std::string scheme() const {
+  // The authentication scheme of the challenge.
+  const HttpAuth::Scheme scheme() const {
     return scheme_;
   }
 
@@ -161,10 +163,10 @@
   // Returns true if |dir| is contained within the realm's protection space.
   bool HasEnclosingPath(const std::string& dir);
 
-  // |origin_| contains the {scheme, host, port} of the server.
+  // |origin_| contains the {protocol, host, port} of the server.
   GURL origin_;
   std::string realm_;
-  std::string scheme_;
+  HttpAuth::Scheme scheme_;
 
   // Identity.
   std::string auth_challenge_;