Fix AudioCapturer implementation to read from audio pipe even when there are no active clients.

remoting/host/linux/audio_pipe_reader.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 REMOTING_HOST_LINUX_AUDIO_PIPE_READER_H_
+#define REMOTING_HOST_LINUX_AUDIO_PIPE_READER_H_
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/ref_counted_memory.h"
+#include "base/message_loop.h"
+#include "base/observer_list_threadsafe.h"
+#include "base/time.h"
+#include "base/timer.h"
+
+class FilePath;
+
+namespace remoting {
+
+// AudioPipeReader class reads from a named pipe to which an audio server (e.g.
+// pulseaudio) writes the sound that's being played back and then sends data to
+// all registered observers.
+class AudioPipeReader
+    : public base::RefCountedThreadSafe<AudioPipeReader>,
+      public MessageLoopForIO::Watcher {
+ public:
+  class StreamObserver {
+   public:
+    virtual void OnDataRead(scoped_refptr<base::RefCountedString> data) = 0;
+  };
+
+  // |task_runner| defines the IO thread on which the object will be reading
+  // data from the pipe.
+  AudioPipeReader(
+      scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+      const FilePath& pipe_name);
+
+  // Register or unregister an observer. Each observer receives data on the
+  // thread on which it was registered and guaranteed not to be called after
+  // RemoveObserver().
+  void AddObserver(StreamObserver* observer);
+  void RemoveObserver(StreamObserver* observer);
+
+  // MessageLoopForIO::Watcher interface.
+  virtual void OnFileCanReadWithoutBlocking(int fd) OVERRIDE;
+  virtual void OnFileCanWriteWithoutBlocking(int fd) OVERRIDE;
+
+ private:
+  friend class base::RefCountedThreadSafe<AudioPipeReader>;
+  virtual ~AudioPipeReader();
+
+  void StartOnAudioThread(const FilePath& pipe_name);
+  void StartTimer();
+  void DoCapture();
+  void WaitForPipeReadable();
+
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+
+  int pipe_fd_;
+  base::RepeatingTimer<AudioPipeReader> timer_;
+  scoped_refptr<ObserverListThreadSafe<StreamObserver> > observers_;
+
+  // Time when capturing was started.
+  base::TimeTicks started_time_;
+
+  // Stream position of the last capture.
+  int64 last_capture_samples_;
+
+  // Bytes left from the previous read.
+  std::string left_over_bytes_;
+
+  MessageLoopForIO::FileDescriptorWatcher file_descriptor_watcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(AudioPipeReader);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_LINUX_AUDIO_PIPE_READER_H_