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

gpu/command_buffer/service/mailbox_manager.h

Index: gpu/command_buffer/service/mailbox_manager.h
diff --git a/gpu/command_buffer/service/mailbox_manager.h b/gpu/command_buffer/service/mailbox_manager.h
index 8b53ce4c14da0a3074f173a6f28983d1116de46f..9f9a6b01db3fcd3a2ca9b0ed3bb25f1190631fd8 100644
--- a/gpu/command_buffer/service/mailbox_manager.h
+++ b/gpu/command_buffer/service/mailbox_manager.h
@@ -15,7 +15,9 @@ namespace gles2 {
 class Texture;
 
 // Manages resources scoped beyond the context or context group level.
-class GPU_EXPORT MailboxManager : public base::RefCounted<MailboxManager> {
+// TODO(mgiuca): Avoid using UnsafeRefCounted. http://crbug.com/469952.
+class GPU_EXPORT MailboxManager
+    : public base::UnsafeRefCounted<MailboxManager> {
  public:
   // Look up the texture definition from the named mailbox.
   virtual Texture* ConsumeTexture(const Mailbox& mailbox) = 0;
@@ -38,7 +40,7 @@ class GPU_EXPORT MailboxManager : public base::RefCounted<MailboxManager> {
   virtual ~MailboxManager() {}
 
  private:
-  friend class base::RefCounted<MailboxManager>;
+  friend class base::UnsafeRefCounted<MailboxManager>;
 
   DISALLOW_COPY_AND_ASSIGN(MailboxManager);
 };