Add FakeVideoDecoder.

media/filters/fake_video_decoder.h

Index: media/filters/fake_video_decoder.h
diff --git a/media/filters/fake_video_decoder.h b/media/filters/fake_video_decoder.h
new file mode 100644
index 0000000000000000000000000000000000000000..f389c4da12d17821c1d919ec37c6ca482bf35b9f
--- /dev/null
+++ b/media/filters/fake_video_decoder.h
@@ -0,0 +1,151 @@
+// Copyright (c) 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 MEDIA_FILTERS_FAKE_VIDEO_DECODER_H_
+#define MEDIA_FILTERS_FAKE_VIDEO_DECODER_H_
+
+#include <list>
+
+#include "base/bind.h"
+#include "base/callback.h"
+#include "base/memory/weak_ptr.h"
+#include "media/base/decoder_buffer.h"
+#include "media/base/demuxer_stream.h"
+#include "media/base/media_export.h"
+#include "media/base/pipeline_status.h"
+#include "media/base/video_decoder.h"
+#include "media/base/video_decoder_config.h"
+#include "media/base/video_frame.h"
+#include "ui/gfx/size.h"
+
+namespace base {
+class MessageLoopProxy;
+}
+
+namespace media {
+
+class MEDIA_EXPORT FakeVideoDecoder : public VideoDecoder {
+ public:
+  // Constructs an object with a decoding delay of |decoding_delay| frames.
+  explicit FakeVideoDecoder(int decoding_delay);
+  virtual ~FakeVideoDecoder();
+
+  // VideoDecoder implementation.
+  virtual void Initialize(DemuxerStream* stream,
+                          const PipelineStatusCB& status_cb,
+                          const StatisticsCB& statistics_cb) OVERRIDE;
+  virtual void Read(const ReadCB& read_cb) OVERRIDE;
+  virtual void Reset(const base::Closure& closure) OVERRIDE;
+  virtual void Stop(const base::Closure& closure) OVERRIDE;
+
+  // Holds the next read/reset/stop callback from firing.
+  void HoldNextRead();
+  void HoldNextReset();
+  void HoldNextStop();
+
+  // Satisfies the pending read/reset/stop callback, which must be ready to fire
+  // when these methods are called.
+  void SatisfyRead();
+  void SatisfyReset();
+  void SatisfyStop();
+
+ private:
+  enum State {
+    UNINITIALIZED,
+    NORMAL
+  };
+
+  // A helper class that can hold a callback from being fired.
+  template <typename CB> class CallbackHolder {

[scherkus (not reviewing), 2013/05/09 20:07:09]

this is complex enough that I feel it should warrant a separate file + docs w/
example usage + simple unit tests

[xhwang, 2013/05/22 04:29:42]

Done.

+   public:
+    CallbackHolder() : hold_callback_(false) {}
+
+    ~CallbackHolder()  {
+      // Make sure all callbacks are satisfied!
+      DCHECK(!hold_callback_);
+      DCHECK(original_cb_.is_null());
+      DCHECK(held_cb_.is_null());
+    }
+
+    // Sets the callback to be potentially held.
+    void SetCallback(const CB& cb) {
+      DCHECK(original_cb_.is_null());
+      DCHECK(held_cb_.is_null());
+      original_cb_ = cb;
+    }
+
+    bool is_null() const {
+      return original_cb_.is_null() && held_cb_.is_null();
+    }
+
+    // Holds the callback when Run() is called.
+    void HoldCallback() { hold_callback_ = true; }
+
+    // Runs or holds the callback as specified by |hold_next_callback_|.

[scherkus (not reviewing), 2013/05/09 20:07:09]

s/hold_next_callback_/hold_callback_/

[xhwang, 2013/05/22 04:29:42]

Done.

+    // This method has overloaded versions to support different types of CB.
+    void Run() {

[scherkus (not reviewing), 2013/05/09 20:07:09]

I don't like how CH emulates the regular API but does things very differently
under the hood. For example:

regular_cb_.Run();  // Looks like a permanent callback.
holder_cb_.Run();  // Might hold. If runs, it resets the cb and is_null() = true

Also if hold_callback_ == true, is it correct that is_null() == false after
Run() is called?

Perhaps some of this can be solved with better function names :)

[xhwang, 2013/05/22 04:29:42]

Done.

+      DCHECK(held_cb_.is_null());
+      if (hold_callback_)
+        held_cb_ = base::Bind(ResetAndReturn(&original_cb_));

[scherkus (not reviewing), 2013/05/09 20:07:09]

nit: base::Bind() not needed

[xhwang, 2013/05/22 04:29:42]

Done.

+      else
+        ResetAndReturn(&original_cb_).Run();
+    }
+
+    template <typename A1, typename A2> void Run(A1 a1, A2 a2) {
+      if (hold_callback_)
+        held_cb_ =
+            base::Bind(ResetAndReturn(&original_cb_), a1, a2);
+      else
+        ResetAndReturn(&original_cb_).Run(a1, a2);
+    }
+
+    // Releases and runs the held callback.
+    void Release() {

[scherkus (not reviewing), 2013/05/09 20:07:09]

RunHeldCallback()?

[xhwang, 2013/05/22 04:29:42]

Done.

+      DCHECK(hold_callback_);
+      DCHECK(!held_cb_.is_null());
+      hold_callback_ = false;
+      ResetAndReturn(&held_cb_).Run();
+    }
+
+   private:
+    bool hold_callback_;
+    CB original_cb_;
+    base::Closure held_cb_;
+  };
+
+  void ReadFromDemuxerStream();
+
+  // Callback for DemuxerStream::Read().
+  void BufferReady(DemuxerStream::Status status,
+                   const scoped_refptr<DecoderBuffer>& buffer);
+
+  void DoReset();
+  void DoStop();
+
+  scoped_refptr<base::MessageLoopProxy> message_loop_;
+  base::WeakPtrFactory<FakeVideoDecoder> weak_factory_;
+  base::WeakPtr<FakeVideoDecoder> weak_this_;
+
+  const int decoding_delay_;
+
+  State state_;
+
+  StatisticsCB statistics_cb_;
+  CallbackHolder<ReadCB> read_cb_;
+  CallbackHolder<base::Closure> reset_cb_;
+  CallbackHolder<base::Closure> stop_cb_;
+
+  // Pointer to the demuxer stream that will feed us compressed buffers.
+  DemuxerStream* demuxer_stream_;
+
+  VideoDecoderConfig current_config_;
+
+  std::list<scoped_refptr<VideoFrame> > decoded_frames_;
+
+  DISALLOW_COPY_AND_ASSIGN(FakeVideoDecoder);
+};
+
+}  // namespace media
+
+#endif  // MEDIA_FILTERS_FAKE_VIDEO_DECODER_H_