Add ntlm to the list of auth protocols

BUG=590689

Review URL: https://codereview.chromium.org/1754013002

Cr-Commit-Position: refs/heads/master@{#378638}
diff --git a/android_webview/browser/net/aw_url_request_context_getter.cc b/android_webview/browser/net/aw_url_request_context_getter.cc
index 600ea178..08ef8df 100644
--- a/android_webview/browser/net/aw_url_request_context_getter.cc
+++ b/android_webview/browser/net/aw_url_request_context_getter.cc
@@ -311,7 +311,8 @@
 
   // In Chrome this is configurable via the AuthSchemes policy. For WebView
   // there is no interest to have it available so far.
-  std::vector<std::string> supported_schemes = {"basic", "digest", "negotiate"};
+  std::vector<std::string> supported_schemes = {"basic", "digest", "ntlm",
+                                                "negotiate"};
   http_auth_preferences_.reset(new net::HttpAuthPreferences(supported_schemes));
 
   UpdateServerWhitelist();