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

chrome/browser/ui/webui/help/version_updater_mac.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.
 
 #include "chrome/browser/ui/webui/help/version_updater_mac.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
+#include "base/strings/stringprintf.h"
+#include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/lifetime/application_lifetime.h"
 #import "chrome/browser/mac/keystone_glue.h"
 #include "chrome/browser/obsolete_system/obsolete_system.h"
 #include "chrome/grit/chromium_strings.h"
 #include "chrome/grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 
 // KeystoneObserver is a simple notification observer for Keystone status
 // updates. It will be created and managed by VersionUpdaterMac.
 @interface KeystoneObserver : NSObject {
@@ skipping 106 matching lines @@
 }
 
 void VersionUpdaterMac::RelaunchBrowser() const {
   // Tell the Broweser to restart if possible.
   chrome::AttemptRestart();
 }
 
 void VersionUpdaterMac::UpdateStatus(NSDictionary* dictionary) {
   AutoupdateStatus keystone_status = static_cast<AutoupdateStatus>(
       [[dictionary objectForKey:kAutoupdateStatusStatus] intValue]);
+  const char* keystone_errors_utf8 =
+      [[dictionary objectForKey:kAutoupdateStatusErrorMessages] UTF8String];
 
   bool enable_promote_button = true;
   base::string16 message;
 
   Status status;
   switch (keystone_status) {
     case kAutoupdateRegistering:
     case kAutoupdateChecking:
       status = CHECKING;
       enable_promote_button = false;
@@ skipping 59 matching lines @@
             l10n_util::GetStringUTF16(IDS_PRODUCT_NAME);
         message = l10n_util::GetStringFUTF16(IDS_PROMOTE_INFOBAR_TEXT,
                                              product_name);
       }
       break;
 
     default:
       NOTREACHED();
       return;
   }
+
+  // If there are any specific error messages being passed along by Keystone,
+  // include them in a <pre> block.
+  if (!message.empty() &&
+      keystone_errors_utf8 && strlen(keystone_errors_utf8)) {
+    // TODO: Should we localize the "Error details" string?  If so, get the
+    // string translated and into GRD, then replace this StringPrintf call
+    // with a call to l10n_util::GetStringFUTF16(IDS_KEYSTONE_ERROR_DETAILS).
+    std::string formatted_errors =
+        base::StringPrintf("<br/><br/>Error details:<br/><pre>%s</pre>",
+                           keystone_errors_utf8);

[Boris Vidolov, 2016/03/08 22:32:52]

The code needs to sanitize the contents of keystone_errors_utf8. '<' and '>' are
common in the Keystone errors. I am not that familiar with the Chrome code base,
but I would assume that there is code for XML/HTML escaping/sanitization. 
If not, you can use the GTM code, which is already imported by Chrome with
-[NSString gtm_stringByEscapingForHTML]

+    message += base::UTF8ToUTF16(formatted_errors.c_str());
+  }
+
   if (!status_callback_.is_null())
     status_callback_.Run(status, 0, message);
 
   if (!promote_callback_.is_null()) {
     PromotionState promotion_state = PROMOTE_HIDDEN;
     if (show_promote_button_)
       promotion_state = enable_promote_button ? PROMOTE_ENABLED
                                               : PROMOTE_DISABLED;
     promote_callback_.Run(promotion_state);
   }
@@ skipping 16 matching lines @@
   } else if (recent_status == kAutoupdatePromoting ||
              recent_status == kAutoupdatePromoteFailed) {
     // Show promotion UI because the user either just clicked that button or
     // because the user should be able to click it again.
     show_promote_button_ = true;
   } else {
     // Show the promote button if promotion is a possibility.
     show_promote_button_ = [keystone_glue wantsPromotion];
   }
 }