Adding --disable-plugins-discovery command line switch to not load third-party plugins from common …

webkit/plugins/npapi/plugin_list_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 "webkit/plugins/npapi/plugin_list.h"
 
 #import <Carbon/Carbon.h>
 #import <Foundation/Foundation.h>
 
 #include "base/file_util.h"
@@ skipping 257 matching lines @@
   // get the info
 
   if (ReadPlistPluginInfo(filename, bundle.get(), info))
     return true;
 
   // ... or not
 
   return false;
 }
 
-void PluginList::GetPluginDirectories(std::vector<base::FilePath>* plugin_dirs) {
+void PluginList::GetPluginDirectories(
+    std::vector<base::FilePath>* plugin_dirs) {
+  if (PluginList::plugins_discovery_disabled_)
+    return;
+
   // Load from the user's area
   GetPluginCommonDirectory(plugin_dirs, true);
 
   // Load from the machine-wide area
   GetPluginCommonDirectory(plugin_dirs, false);
 }
 
 void PluginList::GetPluginsInDir(
     const base::FilePath& path, std::vector<base::FilePath>* plugins) {
   base::FileEnumerator enumerator(path,
                                   false, // not recursive
                                   base::FileEnumerator::DIRECTORIES);
   for (base::FilePath path = enumerator.Next(); !path.value().empty();
        path = enumerator.Next()) {
     plugins->push_back(path);
   }
 }
 
 bool PluginList::ShouldLoadPluginUsingPluginList(
     const WebPluginInfo& info,
     std::vector<webkit::WebPluginInfo>* plugins) {
   return !IsBlacklistedPlugin(info);
 }
 
 }  // namespace npapi
 }  // namespace webkit