Make it possible to have 1 PpapiGlobals per thread. Update unit tests.

ppapi/shared_impl/ppapi_globals.cc

 // Copyright (c) 2011 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.
 
 #include "ppapi/shared_impl/ppapi_globals.h"
 
 #include "base/logging.h"
 
 namespace ppapi {
 
 PpapiGlobals* PpapiGlobals::ppapi_globals_ = NULL;
+base::ThreadLocalPointer<PpapiGlobals> PpapiGlobals::ppapi_globals_for_test_;
 
 PpapiGlobals::PpapiGlobals() {
   DCHECK(!ppapi_globals_);
   ppapi_globals_ = this;
 }
 
+PpapiGlobals::PpapiGlobals(ForTest) {
+  DCHECK(!ppapi_globals_);
+}
+
 PpapiGlobals::~PpapiGlobals() {
-  DCHECK(ppapi_globals_ == this);
+  DCHECK(ppapi_globals_ == this || !ppapi_globals_);
   ppapi_globals_ = NULL;
 }
 
+// static
+void PpapiGlobals::SetPpapiGlobalsOnThreadForTest(PpapiGlobals* ptr) {
+  // If we're using a per-thread PpapiGlobals, we should not have a global one.
+  // If we allowed it, it would always over-ride the "test" versions.
+  DCHECK(!ppapi_globals_);
+  ppapi_globals_for_test_.Set(ptr);
+}
+
 }  // namespace ppapi