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/logging.h"
+#include "base/mac/foundation_util.h"
+#include "base/strings/stringprintf.h"
+#include "base/strings/sys_string_conversions.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 "net/base/escape.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 {
  @private
   VersionUpdaterMac* versionUpdater_;  // Weak.
 }
 
 // Initialize an observer with an updater. The updater owns this object.
@@ skipping 100 matching lines @@
   // registration is in progress and subsequently that it has completed.
 }
 
 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]);
+      [base::mac::ObjCCastStrict<NSNumber>(
+          [dictionary objectForKey:kAutoupdateStatusStatus]) intValue]);
+  std::string error_messages = base::SysNSStringToUTF8(
+      base::mac::ObjCCastStrict<NSString>(
+          [dictionary objectForKey:kAutoupdateStatusErrorMessages]));
 
   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 detailed error messages being passed along by Keystone,
+  // log them. If we have an error to display, include the detail messages
+  // below the error in a <pre> block. Don't bother displaying detail messages
+  // on a success/in-progress/indeterminate status.
+  if (!error_messages.empty()) {
+    VLOG(1) << "Update error messages: " << error_messages;
+
+    if (status == FAILED) {
+      if (!message.empty()) {
+        message += base::UTF8ToUTF16("<br/><br/>");
+      }
+
+      message += l10n_util::GetStringUTF16(IDS_UPGRADE_ERROR_DETAILS);
+      message += base::UTF8ToUTF16("<br/><pre>");
+      message += base::UTF8ToUTF16(net::EscapeForHTML(error_messages));
+      message += base::UTF8ToUTF16("</pre>");

[xiyuan, 2016/03/24 22:14:15]

nit: String cancat is not i18n friendly. We should make
IDS_UPGRADE_ERROR_DETAILS a template with placeholders,

e.g.
in resources.grd
<message name="IDS_UPGRADE_ERROR_DETAILS ...
  Error details:<ph name="BR">&lt;br/&gt;</ph>
  <ph name="BEGIN_PRE">&lt;pre&gt;</ph>
  <ph name="ERROR_DETAILS">%1<ex>A detailed error message.</ex></ph>
  <ph name="END_PRE">&lt;/pre&gt;</ph>
</message>

and here:
message += l10n_util::GetStringFUTF16(IDS_UPGRADE_ERROR_DETAILS,
                                      net::EscapeForHTML(error_messages));

still not ideal though because details string is still concated to |message|.

+    }
+  }
+
   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];
   }
 }