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 d19f6861c162b2a289d2ca1ccf85a13f3d21bf66..6384f2b667ae796490cf7a4e8b68df38ba485871 100644
--- a/content/browser/plugin_service_impl.cc
+++ b/content/browser/plugin_service_impl.cc
@@ -144,7 +144,7 @@ PluginServiceImpl* PluginServiceImpl::GetInstance() {
 }
 
 PluginServiceImpl::PluginServiceImpl()
-    : filter_(NULL) {
+    : npapi_plugins_enabled_(false), filter_(NULL) {
   // Collect the total number of browser processes (which create
   // PluginServiceImpl objects, to be precise). The number is used to normalize
   // the number of processes which start at least one NPAPI/PPAPI Flash process.
@@ -181,6 +181,9 @@ 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() {
@@ -779,17 +782,17 @@ void PluginServiceImpl::GetInternalPlugins(
 }
 
 bool PluginServiceImpl::NPAPIPluginsSupported() {
-#if defined(OS_WIN) || defined(OS_MACOSX)
-  return true;
-#else
-  return false;
-#endif
+  return npapi_plugins_enabled_;
 }
 
 void PluginServiceImpl::DisablePluginsDiscoveryForTesting() {
   PluginList::Singleton()->DisablePluginsDiscovery();
 }
 
+void PluginServiceImpl::EnableNpapiPluginsForTesting() {
+  npapi_plugins_enabled_ = true;
+}
+
 #if defined(OS_MACOSX)
 void PluginServiceImpl::AppActivated() {
   BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,