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

components/nacl/loader/nacl_ipc_adapter.cc

Index: components/nacl/loader/nacl_ipc_adapter.cc
diff --git a/components/nacl/loader/nacl_ipc_adapter.cc b/components/nacl/loader/nacl_ipc_adapter.cc
index 5df92fbe6adb4ef6e1bcf56b2bba334f19bc1469..ac8ac8db7d229787c78a190ff2e61ec5df3af365 100644
--- a/components/nacl/loader/nacl_ipc_adapter.cc
+++ b/components/nacl/loader/nacl_ipc_adapter.cc
@@ -232,8 +232,9 @@ class NaClDescWrapper {
 
 }  // namespace
 
+// TODO(mgiuca): Avoid using UnsafeRefCounted. http://crbug.com/469952.
 class NaClIPCAdapter::RewrittenMessage
-    : public base::RefCounted<RewrittenMessage> {
+    : public base::UnsafeRefCounted<RewrittenMessage> {
  public:
   RewrittenMessage();
 
@@ -249,7 +250,7 @@ class NaClIPCAdapter::RewrittenMessage
   size_t desc_count() const { return descs_.size(); }
 
  private:
-  friend class base::RefCounted<RewrittenMessage>;
+  friend class base::UnsafeRefCounted<RewrittenMessage>;
   ~RewrittenMessage() {}
 
   scoped_ptr<char[]> data_;