Infobar unknown plugins by default on Linux

The user will be asked for confirmation via an infobar before we let any
of the dangerous unknown plugins installed by default on many Linux
distributions run.

BUG=
TEST=


Review URL: https://chromiumcodereview.appspot.com/10821042

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@148682 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/renderer_host/plugin_info_message_filter.cc

@@ -160,8 +160,14 @@ void PluginInfoMessageFilter::Context::DecidePluginStatus(
   DCHECK(plugin_setting != CONTENT_SETTING_DEFAULT);
 
 #if defined(ENABLE_PLUGIN_INSTALLATION)
+#if defined(OS_LINUX)
+  // On Linux, unknown plugins require authorization.
+  PluginInstaller::SecurityStatus plugin_status =
+      PluginInstaller::SECURITY_STATUS_REQUIRES_AUTHORIZATION;
+#else
   PluginInstaller::SecurityStatus plugin_status =
       PluginInstaller::SECURITY_STATUS_UP_TO_DATE;
+#endif
   PluginInstaller* installer =
       plugin_finder->FindPluginWithIdentifier(group->identifier());
   if (installer)