PPAPI: Add new PPB_FileRef.MakeDirectory to support exclusive operation

ppapi/proxy/interface_list.cc

Index: ppapi/proxy/interface_list.cc
diff --git a/ppapi/proxy/interface_list.cc b/ppapi/proxy/interface_list.cc
index bf4a938f025cead1eb59d46ee776bbf6deac5008..6ff3f811baaf600ae0b322c0475033ca89bb01b5 100644
--- a/ppapi/proxy/interface_list.cc
+++ b/ppapi/proxy/interface_list.cc
@@ -193,12 +193,8 @@ InterfaceList::InterfaceList() {
 #endif  // !defined(OS_NACL)
   }
   {
-    // TODO(teravest): These lines should be uncommented when a dev channel
-    // interface is added.  They're commented right now because they cause an
-    // unused variable warning.
-    //
-    // Permission current_required_permission = PERMISSION_DEV_CHANNEL;
-    // #include "ppapi/thunk/interfaces_ppb_public_dev_channel.h"
+    Permission current_required_permission = PERMISSION_DEV_CHANNEL;
+    #include "ppapi/thunk/interfaces_ppb_public_dev_channel.h"
   }
 
   #undef PROXIED_API