Pepper: Var keeps invalid var_id if VarTracker release it and there is another reference

ppapi/shared_impl/var_tracker.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/var_tracker.h"
 
 #include <limits>
 
 #include "base/logging.h"
 #include "ppapi/shared_impl/id_assignment.h"
@@ skipping 82 matching lines @@
   info.ref_count--;
 
   if (info.ref_count == 0) {
     if (info.var->GetType() == PP_VARTYPE_OBJECT) {
       // Objects have special requirements and may not necessarily be released
       // when the refcount goes to 0.
       ObjectGettingZeroRef(found);
     } else {
       // All other var types can just be released.
       DCHECK(info.track_with_no_reference_count == 0);
+      info.var->ResetVarID();
       live_vars_.erase(found);
     }
   }
   return true;
 }
 
 bool VarTracker::ReleaseVar(const PP_Var& var) {
   if (!IsVarTypeRefcounted(var.type))
     return false;
   return ReleaseVar(static_cast<int32>(var.value.as_id));
@@ skipping 39 matching lines @@
 
 bool VarTracker::DeleteObjectInfoIfNecessary(VarMap::iterator iter) {
   if (iter->second.ref_count != 0 ||
       iter->second.track_with_no_reference_count != 0)
     return false;  // Object still alive.
   live_vars_.erase(iter);
   return true;
 }
 
 }  // namespace ppapi