Block NPAPI plugins by default

content/browser/plugin_service_impl.cc

Index: content/browser/plugin_service_impl.cc
diff --git a/content/browser/plugin_service_impl.cc b/content/browser/plugin_service_impl.cc
index 1b7ad7641c43cbb8d517b76869f17def73732935..3b8c2197ed91deac303d0658a7097b9f25fc802d 100644
--- a/content/browser/plugin_service_impl.cc
+++ b/content/browser/plugin_service_impl.cc
@@ -190,6 +190,9 @@ void PluginServiceImpl::Init() {
 
   if (command_line->HasSwitch(switches::kDisablePluginsDiscovery))
     PluginList::Singleton()->DisablePluginsDiscovery();
+#if defined(OS_WIN) || defined(OS_MACOSX)
+  npapi_plugins_enabled_ = command_line->HasSwitch(switches::kEnableNpapi);
+#endif
 }
 
 void PluginServiceImpl::StartWatchingPlugins() {
@@ -801,7 +804,7 @@ void PluginServiceImpl::GetInternalPlugins(
 
 bool PluginServiceImpl::NPAPIPluginsSupported() {
 #if defined(OS_WIN) || defined(OS_MACOSX)
-  return true;
+  return npapi_plugins_enabled_;
 #else
   return false;
 #endif
@@ -811,6 +814,12 @@ void PluginServiceImpl::DisablePluginsDiscoveryForTesting() {
   PluginList::Singleton()->DisablePluginsDiscovery();
 }
 
+#if defined(OS_WIN) || defined(OS_MACOSX)
+void PluginServiceImpl::EnableNpapiPluginsForTesting() {
+  npapi_plugins_enabled_ = true;
+}
+#endif
+
 #if defined(OS_MACOSX)
 void PluginServiceImpl::AppActivated() {
   BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,