Pepper: Delete FileDownloader in trusted plugin.

ppapi/native_client/src/trusted/plugin/callback_source.h

-// Copyright (c) 2012 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 NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_CALLBACK_SOURCE_H
-#define NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_CALLBACK_SOURCE_H
-
-#include "ppapi/cpp/completion_callback.h"
-
-namespace plugin {
-
-// Classes that implement this interface can be used with FileDownloader's
-// DOWNLOAD_STREAM mode. For each chunk of the file as it downloads,
-// The FileDownloader will get a callback of type
-// pp::CompletionCallbackWithOutput<std::vector<char>*> using the
-// GetCallback function, and call it immediately, passing a pointer to a
-// vector with the data as the output field. The class is templatized just
-// in case there are any other use cases in the future.
-// This class really only exists as a way to get callbacks
-// bound to an object (i.e. we don't need the asynchronous behavior of PPAPI)
-// All we really need is tr1::function or base::bind or some such, but we don't
-// have those in the plugin.
-
-template<class T>
-class CallbackSource {
- public:
-  virtual ~CallbackSource();
-  // Returns a callback from callback_factory's NewCallbackWithOutput,
-  // bound to the implementing object.
-  virtual pp::CompletionCallbackWithOutput<T> GetCallback() = 0;
-};
-}
-#endif // NATIVE_CLIENT_SRC_TRUSTED_PLUGIN_CALLBACK_SOURCE_H