Ignore UTF-8's BOM when parsing userscript's metadata.

chrome/browser/extensions/user_script_master.cc

 // Copyright (c) 2008 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/extensions/user_script_master.h"
 
 #include <string>
 #include <vector>
 
 #include "base/file_path.h"
@@ skipping 28 matching lines @@
     : master_(master) {
   CHECK(ChromeThread::GetCurrentThreadIdentifier(&master_thread_id_));
 }
 
 // static
 bool UserScriptMaster::ScriptReloader::ParseMetadataHeader(
       const base::StringPiece& script_text, UserScript* script) {
   // http://wiki.greasespot.net/Metadata_block
   base::StringPiece line;
   size_t line_start = 0;
-  size_t line_end = 0;
+
+  // Skip UTF-8's BOM.
+  if (script_text.starts_with(kUtf8ByteOrderMark))
+    line_start += strlen(kUtf8ByteOrderMark);
+
+  size_t line_end = line_start;
   bool in_metadata = false;
 
   static const base::StringPiece kUserScriptBegin("// ==UserScript==");
   static const base::StringPiece kUserScriptEng("// ==/UserScript==");
   static const base::StringPiece kNamespaceDeclaration("// @namespace ");
   static const base::StringPiece kNameDeclaration("// @name ");
   static const base::StringPiece kDescriptionDeclaration("// @description ");
   static const base::StringPiece kIncludeDeclaration("// @include ");
   static const base::StringPiece kExcludeDeclaration("// @exclude ");
   static const base::StringPiece kMatchDeclaration("// @match ");
@@ skipping 331 matching lines @@
       DCHECK(false);
   }
 }
 
 void UserScriptMaster::StartScan() {
   if (!script_reloader_)
     script_reloader_ = new ScriptReloader(this);
 
   script_reloader_->StartScan(user_script_dir_, lone_scripts_);
 }