Revert 187340 "PPAPI: Remove threading options; it's always on"

ppapi/shared_impl/test_globals.h

 // 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.
 
 #ifndef PPAPI_SHARED_IMPL_TEST_GLOBALS_H_
 #define PPAPI_SHARED_IMPL_TEST_GLOBALS_H_
 
 #include "base/compiler_specific.h"
 #include "ppapi/shared_impl/callback_tracker.h"
 #include "ppapi/shared_impl/ppapi_globals.h"
 #include "ppapi/shared_impl/resource_tracker.h"
 #include "ppapi/shared_impl/var_tracker.h"
 
 namespace ppapi {
 
 class TestVarTracker : public VarTracker {
  public:
-  TestVarTracker() : VarTracker(THREAD_SAFE) {}
+  TestVarTracker() {}
   virtual ~TestVarTracker() {}
   virtual ArrayBufferVar* CreateArrayBuffer(uint32 size_in_bytes) OVERRIDE {
     return NULL;
   }
   virtual void DidDeleteInstance(PP_Instance instance) OVERRIDE {
   }
 };
 
 // Implementation of PpapiGlobals for tests that don't need either the host- or
 // plugin-specific implementations.
@@ skipping 33 matching lines @@
   ResourceTracker resource_tracker_;
   TestVarTracker var_tracker_;
   scoped_refptr<CallbackTracker> callback_tracker_;
 
   DISALLOW_COPY_AND_ASSIGN(TestGlobals);
 };
 
 }  // namespace ppapi
 
 #endif   // PPAPI_SHARED_IMPL_TEST_GLOBALS_H_