[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 5b7fbce4c7eeb7c796fcefc7e77bd10c1060a799..d045e284beb1de0ae9ff880164b87c38a5f0567f 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[];
@@ -213,6 +214,7 @@ 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[];