PolicyDomainDescriptor must be RefCountedThreadSafe.

chrome/browser/policy/policy_domain_descriptor.h

Index: chrome/browser/policy/policy_domain_descriptor.h
diff --git a/chrome/browser/policy/policy_domain_descriptor.h b/chrome/browser/policy/policy_domain_descriptor.h
index b5f71151e5799e818a9ad2009485288265a7014c..daa3d565e4ed148f82c6e3743d4c5230f45c01d3 100644
--- a/chrome/browser/policy/policy_domain_descriptor.h
+++ b/chrome/browser/policy/policy_domain_descriptor.h
@@ -20,7 +20,8 @@ class PolicySchema;
 
 // For each policy domain, this class keeps the complete list of valid
 // components for that domain, and the PolicySchema for each component.
-class PolicyDomainDescriptor : public base::RefCounted<PolicyDomainDescriptor> {
+class PolicyDomainDescriptor
+    : public base::RefCountedThreadSafe<PolicyDomainDescriptor> {
  public:
   typedef std::map<std::string, const PolicySchema*> SchemaMap;
 
@@ -40,7 +41,7 @@ class PolicyDomainDescriptor : public base::RefCounted<PolicyDomainDescriptor> {
   void FilterBundle(PolicyBundle* bundle) const;
 
  private:
-  friend class base::RefCounted<PolicyDomainDescriptor>;
+  friend class base::RefCountedThreadSafe<PolicyDomainDescriptor>;
   ~PolicyDomainDescriptor();
 
   PolicyDomain domain_;