[Signin Error Dialog] (2/3) Added handlers and UI constructors

chrome/common/url_constants.h

Index: chrome/common/url_constants.h
diff --git a/chrome/common/url_constants.h b/chrome/common/url_constants.h
index 9b2b2ddd2e2bc290bfc7a033a93bb63489be797b..80c27ed63f45ec1e52708c4b7bf6c93f251212c2 100644
--- a/chrome/common/url_constants.h
+++ b/chrome/common/url_constants.h
@@ -74,6 +74,7 @@ extern const char kChromeUIMdSettingsURL[];
 extern const char kChromeUISettingsURL[];
 extern const char kChromeUIContentSettingsURL[];
 extern const char kChromeUISettingsFrameURL[];
+extern const char kChromeUISigninErrorURL[];
 extern const char kChromeUISiteEngagementHost[];
 extern const char kChromeUISuggestionsURL[];
 extern const char kChromeUISupervisedUserPassphrasePageURL[];
@@ -214,6 +215,7 @@ extern const char kChromeUIRestartHost[];
 extern const char kChromeUISettingsHost[];
 extern const char kChromeUISettingsFrameHost[];
 extern const char kChromeUIShorthangHost[];
+extern const char kChromeUISigninErrorHost[];
 extern const char kChromeUISignInInternalsHost[];
 extern const char kChromeUISuggestionsHost[];
 extern const char kChromeUISupervisedUserInternalsHost[];