Fix erratic HTML5 audio playback

media/audio/audio_output_dispatcher.cc

Index: media/audio/audio_output_dispatcher.cc
diff --git a/media/audio/audio_output_dispatcher.cc b/media/audio/audio_output_dispatcher.cc
index 3f9d848a2c9d1762155e7062aee36f479d6563d0..c70706932cccfb6653fc63e5a116fd229b4224bc 100644
--- a/media/audio/audio_output_dispatcher.cc
+++ b/media/audio/audio_output_dispatcher.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Copyright (c) 2011 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.
 
@@ -6,6 +6,7 @@
 
 #include "base/compiler_specific.h"
 #include "base/message_loop.h"
+#include "base/time.h"
 #include "media/audio/audio_io.h"
 
 AudioOutputDispatcher::AudioOutputDispatcher(
@@ -14,6 +15,8 @@ AudioOutputDispatcher::AudioOutputDispatcher(
     : audio_manager_(audio_manager),
       message_loop_(audio_manager->GetMessageLoop()),
       params_(params),
+      pause_delay_milliseconds_(2 * params.samples_per_packet *
+          base::Time::kMillisecondsPerSecond / params.sample_rate),
       paused_proxies_(0),
       ALLOW_THIS_IN_INITIALIZER_LIST(close_timer_(
           base::TimeDelta::FromMilliseconds(close_delay_ms),
@@ -28,7 +31,7 @@ bool AudioOutputDispatcher::StreamOpened() {
   paused_proxies_++;
 
   // Ensure that there is at least one open stream.
-  if (streams_.empty() && !CreateAndOpenStream()) {
+  if (idle_streams_.empty() && !CreateAndOpenStream()) {
     return false;
   }
 
@@ -40,12 +43,12 @@ bool AudioOutputDispatcher::StreamOpened() {
 AudioOutputStream* AudioOutputDispatcher::StreamStarted() {
   DCHECK_EQ(MessageLoop::current(), message_loop_);
 
-  if (streams_.empty() && !CreateAndOpenStream()) {
+  if (idle_streams_.empty() && !CreateAndOpenStream()) {
     return NULL;
   }
 
-  AudioOutputStream* stream = streams_.back();
-  streams_.pop_back();
+  AudioOutputStream* stream = idle_streams_.back();
+  idle_streams_.pop_back();
 
   DCHECK_GT(paused_proxies_, 0u);
   paused_proxies_--;
@@ -61,20 +64,41 @@ AudioOutputStream* AudioOutputDispatcher::StreamStarted() {
 
 void AudioOutputDispatcher::StreamStopped(AudioOutputStream* stream) {
   DCHECK_EQ(MessageLoop::current(), message_loop_);
+
   paused_proxies_++;
-  streams_.push_back(stream);
+
+  pausing_streams_.push_front(stream);
   close_timer_.Reset();
+
+  // Don't recycle stream until two buffers worth of time has elapsed.
+  message_loop_->PostDelayedTask(
+      FROM_HERE,
+      NewRunnableMethod(this, &AudioOutputDispatcher::StopStreamTask),
+      pause_delay_milliseconds_);
+}
+
+void AudioOutputDispatcher::StopStreamTask() {
+  if (pausing_streams_.empty())
+    return;
+  AudioOutputStream* stream = pausing_streams_.back();
+  pausing_streams_.pop_back();
+  idle_streams_.push_back(stream);
 }
 
 void AudioOutputDispatcher::StreamClosed() {
   DCHECK_EQ(MessageLoop::current(), message_loop_);
 
+  while (!pausing_streams_.empty()) {
+    idle_streams_.push_back(pausing_streams_.back());
+    pausing_streams_.pop_back();
+  }
+
   DCHECK_GT(paused_proxies_, 0u);
   paused_proxies_--;
 
-  while (streams_.size() > paused_proxies_) {
-    streams_.back()->Close();
-    streams_.pop_back();
+  while (idle_streams_.size() > paused_proxies_) {
+    idle_streams_.back()->Close();
+    idle_streams_.pop_back();
   }
 }
 
@@ -92,14 +116,15 @@ bool AudioOutputDispatcher::CreateAndOpenStream() {
     stream->Close();
     return false;
   }
-  streams_.push_back(stream);
+  idle_streams_.push_back(stream);
   return true;
 }
 
 void AudioOutputDispatcher::OpenTask() {
   // Make sure that we have at least one stream allocated if there
   // are paused streams.
-  if (paused_proxies_ > 0 && streams_.empty()) {
+  if (paused_proxies_ > 0 && idle_streams_.empty() &&
+      pausing_streams_.empty()) {
     CreateAndOpenStream();
   }
 
@@ -108,8 +133,8 @@ void AudioOutputDispatcher::OpenTask() {
 
 // This method is called by |close_timer_|.
 void AudioOutputDispatcher::ClosePendingStreams() {
-  while (!streams_.empty()) {
-    streams_.back()->Close();
-    streams_.pop_back();
+  while (!idle_streams_.empty()) {
+    idle_streams_.back()->Close();
+    idle_streams_.pop_back();
   }
 }