Move Renderer permanent callbacks into RendererClient interface.

media/base/renderer_client.h

+// Copyright 2016 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 MEDIA_BASE_RENDERER_CLIENT_H_
+#define MEDIA_BASE_RENDERER_CLIENT_H_
+
+namespace media {
+
+// Interface used by Renderer, AudioRenderer, and VideoRenderer implementations
+// to notify their clients.
+class RendererClient {
+ public:
+  // Executed if any error was encountered after Renderer initialization.
+  virtual void OnError(PipelineStatus status) = 0;
+
+  // Executed when rendering has reached the end of stream.
+  virtual void OnEnded() = 0;
+
+  // Executed periodically with rendering statistics.
+  virtual void OnStatisticsUpdate(const PipelineStatistics& stats) = 0;
+
+  // Executed when buffering state is changed.
+  virtual void OnBufferingStateChange(BufferingState state) = 0;
+
+  // Executed whenever the key needed to decrypt the stream is not available.
+  virtual void OnWaitingForDecryptionKey() = 0;
+};
+
+}  // namespace media
+
+#endif  // MEDIA_BASE_RENDERER_CLIENT_H_