Stop trying to use the italic version of the system font; it doesn't exist.

chrome/browser/ui/autofill/autofill_popup_controller_impl.cc

 // 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/autofill/autofill_popup_controller_impl.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "base/logging.h"
@@ skipping 95 matching lines @@
       text_direction_(text_direction),
       registered_key_press_event_callback_with_(NULL),
       hide_on_outside_click_(false),
       key_press_event_callback_(
           base::Bind(&AutofillPopupControllerImpl::HandleKeyPressEvent,
                      base::Unretained(this))),
       weak_ptr_factory_(this) {
   ClearState();
 #if !defined(OS_ANDROID)
   subtext_font_ = name_font_.DeriveFont(kLabelFontSizeDelta);
+#if defined(OS_MACOSX)
+  // There is no italic version of the system font.
+  warning_font_ = name_font_;
+#else
   warning_font_ = name_font_.DeriveFont(0, gfx::Font::ITALIC);
 #endif
+#endif
 }
 
 AutofillPopupControllerImpl::~AutofillPopupControllerImpl() {}
 
 void AutofillPopupControllerImpl::Show(
     const std::vector<string16>& names,
     const std::vector<string16>& subtexts,
     const std::vector<string16>& icons,
     const std::vector<int>& identifiers) {
   SetValues(names, subtexts, icons, identifiers);
@@ skipping 630 matching lines @@
     // The popup can appear below the field.
     return std::make_pair(bottom_growth_start, popup_required_height);
   } else {
     // The popup must appear above the field.
     return std::make_pair(top_growth_end - popup_required_height,
                           popup_required_height);
   }
 }
 
 }  // namespace autofill