Add mac-only "Set Up Automatic Updates..." button to the new about page.

chrome/browser/mac/keystone_glue.mm

 // 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.
 
 #import "chrome/browser/mac/keystone_glue.h"
 
 #include <sys/mount.h>
 #include <sys/param.h>
 #include <sys/stat.h>
 
@@ skipping 819 matching lines @@
 
   if (statfs(appPathC, &statfsBuf) != 0) {
     PLOG(ERROR) << "statfs";
     // Be optimistic about the filesystem's writability.
     return NO;
   }
 
   return (statfsBuf.f_flags & MNT_RDONLY) != 0;
 }
 
+- (BOOL)isAutoupdateEnabledForAllUsers {
+  return [self isSystemKeystone] && ![self isUserTicket];
+}
+
 - (BOOL)needsPromotion {
   // Don't promote when on a read-only filesystem.
   if ([self isOnReadOnlyFilesystem]) {
     return NO;
   }
 
   // Promotion is required when a system ticket is present but system Keystone
   // is not.
   if ([self isSystemTicketDoomed]) {
     return YES;
@@ skipping 345 matching lines @@
   return [KeystoneGlue defaultKeystoneGlue] != nil;
 }
 
 base::string16 CurrentlyInstalledVersion() {
   KeystoneGlue* keystoneGlue = [KeystoneGlue defaultKeystoneGlue];
   NSString* version = [keystoneGlue currentlyInstalledVersion];
   return base::SysNSStringToUTF16(version);
 }
 
 }  // namespace keystone_glue