Add viewing of error messages from Keystone upon self-update failure.

chrome/browser/mac/keystone_glue.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_MAC_KEYSTONE_GLUE_H_
 #define CHROME_BROWSER_MAC_KEYSTONE_GLUE_H_
 
 #include "base/strings/string16.h"
 
 #if defined(__OBJC__)
@@ skipping 26 matching lines @@
   kAutoupdatePromoteFailed,   // no version
   kAutoupdateNeedsPromotion,  // no version
 };
 
 // kAutoupdateStatusNotification is the name of the notification posted when
 // -checkForUpdate and -installUpdate complete.  This notification will be
 // sent with with its sender object set to the KeystoneGlue instance sending
 // the notification.  Its userInfo dictionary will contain an AutoupdateStatus
 // value as an intValue at key kAutoupdateStatusStatus.  If a version is
 // available (see AutoupdateStatus), it will be present at key
-// kAutoupdateStatusVersion.
+// kAutoupdateStatusVersion.  If any error messages were supplied by Keystone,
+// they will be present at key kAutoupdateStatusErrorMessages.
 extern NSString* const kAutoupdateStatusNotification;
 extern NSString* const kAutoupdateStatusStatus;
 extern NSString* const kAutoupdateStatusVersion;
+extern NSString* const kAutoupdateStatusErrorMessages;
 
 namespace {
 
 enum BrandFileType {
   kBrandFileTypeNotDetermined = 0,
   kBrandFileTypeNone,
   kBrandFileTypeUser,
   kBrandFileTypeSystem,
 };
 
@@ skipping 156 matching lines @@
 
 // True if Keystone is enabled.
 bool KeystoneEnabled();
 
 // The version of the application currently installed on disk.
 base::string16 CurrentlyInstalledVersion();
 
 }  // namespace keystone_glue
 
 #endif  // CHROME_BROWSER_MAC_KEYSTONE_GLUE_H_