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

gpu/command_buffer/service/valuebuffer_manager.h

Index: gpu/command_buffer/service/valuebuffer_manager.h
diff --git a/gpu/command_buffer/service/valuebuffer_manager.h b/gpu/command_buffer/service/valuebuffer_manager.h
index d67616a104b208048f5acc8ec53b3daaeea19b02..b05eab226c1c186a0d1a01ca13fb937834a73bf2 100644
--- a/gpu/command_buffer/service/valuebuffer_manager.h
+++ b/gpu/command_buffer/service/valuebuffer_manager.h
@@ -22,8 +22,9 @@ namespace gles2 {
 
 class ValuebufferManager;
 
+// TODO(mgiuca): Avoid using UnsafeRefCounted. http://crbug.com/469952.
 class GPU_EXPORT SubscriptionRefSet
-    : public base::RefCounted<SubscriptionRefSet> {
+    : public base::UnsafeRefCounted<SubscriptionRefSet> {
  public:
   class GPU_EXPORT Observer {
    public:
@@ -42,7 +43,7 @@ class GPU_EXPORT SubscriptionRefSet
   virtual ~SubscriptionRefSet();
 
  private:
-  friend class base::RefCounted<SubscriptionRefSet>;
+  friend class base::UnsafeRefCounted<SubscriptionRefSet>;
   friend class ValuebufferManager;
 
   typedef base::hash_map<unsigned int, int> RefSet;