Move extensions manifest IconsHandler to //extensions

extensions/common/file_util.h

 // Copyright 2013 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.
 
 #ifndef EXTENSIONS_COMMON_FILE_UTIL_H_
 #define EXTENSIONS_COMMON_FILE_UTIL_H_
 
+#include <string>
+
+class ExtensionIconSet;
 class GURL;
 
 namespace base {
 class FilePath;
 }
 
 namespace extensions {
+class Extension;
+
 namespace file_util {
 
 // Get a relative file path from a chrome-extension:// URL.
 base::FilePath ExtensionURLToRelativeFilePath(const GURL& url);
 
 // Get a full file path from a chrome-extension-resource:// URL, If the URL
 // points a file outside of root, this function will return empty FilePath.
 base::FilePath ExtensionResourceURLToFilePath(const GURL& url,
                                               const base::FilePath& root);
 
+// Returns true if the icons in the icon set exist. Oherwise, populates
+// |error| with the |error_message_id| for an invalid file.
+bool ValidateExtensionIconSet(const ExtensionIconSet& icon_set,
+                              const Extension* extension,
+                              int error_message_id,
+                              std::string* error);
+
 }  // namespace file_util
 }  // namespace extensions
 
 #endif  // EXTENSIONS_COMMON_FILE_UTIL_H_