Revert of Change extension icon load errors to warnings

extensions/utility/unpacker.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 "extensions/utility/unpacker.h"
 
 #include <set>
 #include <utility>
 
 #include "base/files/file_enumerator.h"
@@ skipping 167 matching lines @@
   std::vector<InstallWarning> warnings;
   if (!file_util::ValidateExtension(extension.get(), &error, &warnings)) {
     SetError(error);
     return false;
   }
   extension->AddInstallWarnings(warnings);
 
   // Decode any images that the browser needs to display.
   std::set<base::FilePath> image_paths =
       ExtensionsClient::Get()->GetBrowserImagePaths(extension.get());
-  for (const base::FilePath& path : image_paths) {
-    if (!AddDecodedImage(path))
+  for (std::set<base::FilePath>::iterator it = image_paths.begin();
+       it != image_paths.end(); ++it) {
+    if (!AddDecodedImage(*it))
       return false;  // Error was already reported.
   }
 
   // Parse all message catalogs (if any).
   parsed_catalogs_.reset(new base::DictionaryValue);
   if (!LocaleInfo::GetDefaultLocale(extension.get()).empty()) {
     if (!ReadAllMessageCatalogs(LocaleInfo::GetDefaultLocale(extension.get())))
       return false;  // Error was already reported.
   }
 
@@ skipping 87 matching lines @@
 
 void Unpacker::SetError(const std::string& error) {
   SetUTF16Error(base::UTF8ToUTF16(error));
 }
 
 void Unpacker::SetUTF16Error(const base::string16& error) {
   error_message_ = error;
 }
 
 }  // namespace extensions