cc: Remove some unnecessary const scoped_refptr&.

cc/output/texture_mailbox_deleter.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CC_OUTPUT_TEXTURE_MAILBOX_DELETER_H_
 #define CC_OUTPUT_TEXTURE_MAILBOX_DELETER_H_
 
 #include <vector>
 
 #include "base/memory/weak_ptr.h"
 #include "cc/base/cc_export.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }
 
 namespace gpu {
 struct SyncToken;
 }
 
 namespace cc {
 class ContextProvider;
 class SingleReleaseCallback;
 
 class CC_EXPORT TextureMailboxDeleter {
  public:
   // task_runner corresponds with the thread the delete task should be posted
   // to. If null, the delete will happen on the calling thread.
   explicit TextureMailboxDeleter(
-      const scoped_refptr<base::SingleThreadTaskRunner>& task_runner);
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner);
   ~TextureMailboxDeleter();
 
   // Returns a Callback that can be used as the ReleaseCallback for a
   // TextureMailbox attached to the |texture_id|. The ReleaseCallback can
   // be passed to other threads and will destroy the texture, once it is
   // run, on the impl thread. If the TextureMailboxDeleter is destroyed
   // due to the compositor shutting down, then the ReleaseCallback will
   // become a no-op and the texture will be deleted immediately on the
   // impl thread, along with dropping the reference to the ContextProvider.
   scoped_ptr<SingleReleaseCallback> GetReleaseCallback(
-      const scoped_refptr<ContextProvider>& context_provider,
+      scoped_refptr<ContextProvider> context_provider,
       unsigned texture_id);
 
  private:
   // Runs the |impl_callback| to delete the texture and removes the callback
   // from the |impl_callbacks_| list.
   void RunDeleteTextureOnImplThread(SingleReleaseCallback* impl_callback,
                                     const gpu::SyncToken& sync_token,
                                     bool is_lost);
 
   scoped_refptr<base::SingleThreadTaskRunner> impl_task_runner_;
   std::vector<scoped_ptr<SingleReleaseCallback>> impl_callbacks_;
   base::WeakPtrFactory<TextureMailboxDeleter> weak_ptr_factory_;
 };
 
 }  // namespace cc
 
 #endif  // CC_OUTPUT_TEXTURE_MAILBOX_DELETER_H_