base::RefCounted now DCHECKs when referenced from multiple threads.

gpu/command_buffer/common/value_state.h

Index: gpu/command_buffer/common/value_state.h
diff --git a/gpu/command_buffer/common/value_state.h b/gpu/command_buffer/common/value_state.h
index 478924581b8a13b45d8afd9cfce38f7cbd38b8b5..d39ca752a855c077f93f1eefccd10e4d344cbbdf 100644
--- a/gpu/command_buffer/common/value_state.h
+++ b/gpu/command_buffer/common/value_state.h
@@ -19,7 +19,8 @@ union GPU_EXPORT ValueState {
 };
 
 // Refcounted wrapper for a hash_map of subscription targets to ValueStates
-class GPU_EXPORT ValueStateMap : public base::RefCounted<ValueStateMap> {
+// TODO(mgiuca): Avoid using UnsafeRefCounted. http://crbug.com/469952.
+class GPU_EXPORT ValueStateMap : public base::UnsafeRefCounted<ValueStateMap> {
  public:
   ValueStateMap();
 
@@ -32,7 +33,7 @@ class GPU_EXPORT ValueStateMap : public base::RefCounted<ValueStateMap> {
   virtual ~ValueStateMap();
 
  private:
-  friend class base::RefCounted<ValueStateMap>;
+  friend class base::UnsafeRefCounted<ValueStateMap>;
 
   typedef base::hash_map<unsigned int, ValueState> Map;