Added volume adjust sound behind the flag.

media/audio/sounds/audio_stream_handler.cc

Index: media/audio/sounds/audio_stream_handler.cc
diff --git a/media/audio/sounds/audio_stream_handler.cc b/media/audio/sounds/audio_stream_handler.cc
index 08608ac4187aa0863b777e5e42701f2b7a327f69..d82829189a80fde0da24aa28d01611d821ee290a 100644
--- a/media/audio/sounds/audio_stream_handler.cc
+++ b/media/audio/sounds/audio_stream_handler.cc
@@ -6,10 +6,13 @@
 
 #include <string>
 
+#include "base/cancelable_callback.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop_proxy.h"
+#include "base/time/time.h"
 #include "media/audio/audio_manager.h"
 #include "media/audio/audio_manager_base.h"
+#include "media/audio/sounds/wav_reader.h"
 #include "media/base/channel_layout.h"
 
 namespace media {
@@ -22,6 +25,9 @@ const double kOutputVolumePercent = 0.8;
 // The number of frames each OnMoreData() call will request.
 const int kDefaultFrameCount = 1024;
 
+// Delay between end of sound and call to AudioOutputStream::Stop().
+const int kStopStreamDelaySec = 3;
+
 AudioStreamHandler::TestObserver* g_observer_for_testing = NULL;
 AudioOutputStream::AudioSourceCallback* g_audio_source_for_testing = NULL;
 
@@ -30,36 +36,55 @@ AudioOutputStream::AudioSourceCallback* g_audio_source_for_testing = NULL;
 class AudioStreamHandler::AudioStreamContainer
     : public AudioOutputStream::AudioSourceCallback {
  public:
-  AudioStreamContainer(const WavAudioHandler& wav_audio,
+  AudioStreamContainer(const WavParser& wav_parser,
                        const AudioParameters& params)
       : stream_(NULL),
-        wav_audio_(wav_audio),
+        wav_reader_(new WavReaderImpl(wav_parser)),
+        duration_(wav_parser.duration()),
         params_(params),
-        cursor_(0) {
-  }
+        cursor_(0),
+        num_replay_requests_(0),
+        is_stream_idle_(true),
+        schedule_replay_request_for_testing_(0) {}
 
   virtual ~AudioStreamContainer() {
     DCHECK(AudioManager::Get()->GetMessageLoop()->BelongsToCurrentThread());
+    stop_stream_closure_.Cancel();
+    StopAndCloseStream();
   }
 
   void Play() {
     DCHECK(AudioManager::Get()->GetMessageLoop()->BelongsToCurrentThread());
 
     if (!stream_) {
-      stream_ = AudioManager::Get()->MakeAudioOutputStreamProxy(params_,
-                                                                std::string(),
-                                                                std::string());
+      stream_ = AudioManager::Get()->MakeAudioOutputStreamProxy(
+          params_, std::string(), std::string());
       if (!stream_ || !stream_->Open()) {
         LOG(ERROR) << "Failed to open an output stream.";
         return;
       }
+      cursor_ = 0;
       stream_->SetVolume(kOutputVolumePercent);
+    } else if (is_stream_idle_) {
+      // If stream exists and idle, just stop the stream and start again.
+      cursor_ = 0;
+      StopStream();
     } else {
-      // TODO (ygorshenin@): implement smart stream rewind.
-      stream_->Stop();
+      // Stream exists and not idle, so let the current sound to
+      // finish playing.  If less than |wav_parser_.duration()| / 2
+      // until the end (including all replay requests), then replay is
+      // sheduled.  The main purpose of this strategy is to smooth
+      // sound reproduction when multiple requests are made, for
+      // instance, when user presses volume(up|down) button for a long
+      // time.
+      if (ReplayRequestCouldBeScheduled())
+        ++num_replay_requests_;
+      return;
     }
 
-    cursor_ = 0;
+    last_play_start_time_ = base::TimeTicks::Now();
+    num_replay_requests_ = 0;
+    is_stream_idle_ = false;
     if (g_audio_source_for_testing)
       stream_->Start(g_audio_source_for_testing);
     else
@@ -71,27 +96,40 @@ class AudioStreamHandler::AudioStreamContainer
 
   void Stop() {
     DCHECK(AudioManager::Get()->GetMessageLoop()->BelongsToCurrentThread());
-    if (!stream_)
-      return;
-    stream_->Stop();
-    stream_->Close();
-    stream_ = NULL;
-
-    if (g_observer_for_testing)
-      g_observer_for_testing->OnStop(cursor_);
+    StopStream();
   }
 
  private:
+  friend class AudioStreamHandler;
+
   // AudioOutputStream::AudioSourceCallback overrides:
   // Following methods could be called from *ANY* thread.
   virtual int OnMoreData(AudioBus* dest,
                          AudioBuffersState /* state */) OVERRIDE {
+    if (is_stream_idle_)
+      return 0;
+
     size_t bytes_written = 0;
-    if (wav_audio_.AtEnd(cursor_) ||
-        !wav_audio_.CopyTo(dest, cursor_, &bytes_written)) {
-      AudioManager::Get()->GetMessageLoop()->PostTask(
-          FROM_HERE,
-          base::Bind(&AudioStreamContainer::Stop, base::Unretained(this)));
+    if (wav_reader_->AtEnd(cursor_) ||
+        !wav_reader_->CopyTo(dest, cursor_, &bytes_written)) {
+      // If there are replay requests, |cursor_| is reset and will
+      // continue to play from the start. Otherwise, stream will be
+      // stopped (not closed!) in |kStopStreamDelaySec| seconds,
+      // unless new Play() requests arrive during this time period.
+      if (num_replay_requests_) {
+        cursor_ = 0;
+        --num_replay_requests_;
+        if (g_observer_for_testing)
+          g_observer_for_testing->OnReplay();
+      } else {
+        is_stream_idle_ = true;
+        stop_stream_closure_.Reset(base::Bind(&AudioStreamContainer::StopStream,
+                                              base::Unretained(this)));
+        AudioManager::Get()->GetMessageLoop()->PostDelayedTask(
+            FROM_HERE,
+            stop_stream_closure_.callback(),
+            base::TimeDelta::FromSeconds(kStopStreamDelaySec));
+      }
       return 0;
     }
     cursor_ += bytes_written;
@@ -109,18 +147,65 @@ class AudioStreamHandler::AudioStreamContainer
     LOG(ERROR) << "Error during system sound reproduction.";
   }
 
+  void StopStream() {
+    stop_stream_closure_.Cancel();
+    num_replay_requests_ = 0;
+    if (stream_)
+      stream_->Stop();
+    if (g_observer_for_testing)
+      g_observer_for_testing->OnStop(cursor_);
+  }
+
+  void StopAndCloseStream() {
+    StopStream();
+    if (stream_) {
+      stream_->Close();
+      stream_ = NULL;
+    }
+  }
+
+  bool ReplayRequestCouldBeScheduled() {
+    if (schedule_replay_request_for_testing_) {
+      --schedule_replay_request_for_testing_;
+      return true;
+    }
+    return 2 * (base::TimeTicks::Now() - last_play_start_time_) >
+        (2 * num_replay_requests_ + 1) * duration_;
+  }
+
+  void SetWavReaderForTesting(WavReader* reader) {
+    wav_reader_.reset(reader);
+  }
+
+  void AllowReplayOnceForTesting() {
+    ++schedule_replay_request_for_testing_;
+  }
+
   AudioOutputStream* stream_;
 
-  const WavAudioHandler wav_audio_;
+  scoped_ptr<WavReader> wav_reader_;
+  const base::TimeDelta duration_;
   const AudioParameters params_;
 
   size_t cursor_;
 
+  // Number of pending play requests, which should be processed after
+  // the current request.
+  int num_replay_requests_;
+
+  base::CancelableClosure stop_stream_closure_;
+  bool is_stream_idle_;
+
+  // Last time sound started to play from the start.
+  base::TimeTicks last_play_start_time_;
+
+  int schedule_replay_request_for_testing_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioStreamContainer);
 };
 
 AudioStreamHandler::AudioStreamHandler(const base::StringPiece& wav_data)
-    : wav_audio_(wav_data),
+    : wav_parser_(wav_data),
       initialized_(false) {
   AudioManager* manager = AudioManager::Get();
   if (!manager) {
@@ -128,15 +213,15 @@ AudioStreamHandler::AudioStreamHandler(const base::StringPiece& wav_data)
     return;
   }
   AudioParameters params(AudioParameters::AUDIO_PCM_LOW_LATENCY,
-                         GuessChannelLayout(wav_audio_.num_channels()),
-                         wav_audio_.sample_rate(),
-                         wav_audio_.bits_per_sample(),
+                         GuessChannelLayout(wav_parser_.num_channels()),
+                         wav_parser_.sample_rate(),
+                         wav_parser_.bits_per_sample(),
                          kDefaultFrameCount);
   if (!params.IsValid()) {
     LOG(ERROR) << "Audio params are invalid.";
     return;
   }
-  stream_.reset(new AudioStreamContainer(wav_audio_, params));
+  stream_.reset(new AudioStreamContainer(wav_parser_, params));
   initialized_ = true;
 }
 
@@ -185,4 +270,18 @@ void AudioStreamHandler::SetAudioSourceForTesting(
   g_audio_source_for_testing = source;
 }
 
+void AudioStreamHandler::SetWavReaderForTesting(WavReader* reader) {
+  AudioManager::Get()->GetMessageLoop()->PostTask(
+      FROM_HERE,
+      base::Bind(&AudioStreamContainer::SetWavReaderForTesting,
+                 base::Unretained(stream_.get()), reader));
+}
+
+void AudioStreamHandler::AllowReplayOnceForTesting() {
+  AudioManager::Get()->GetMessageLoop()->PostTask(
+      FROM_HERE,
+      base::Bind(&AudioStreamContainer::AllowReplayOnceForTesting,
+                 base::Unretained(stream_.get())));
+}
+
 }  // namespace media