Improve logging related to start/stop and failure of audio input streams in Chrome

media/audio/audio_manager_base.cc

Index: media/audio/audio_manager_base.cc
diff --git a/media/audio/audio_manager_base.cc b/media/audio/audio_manager_base.cc
index 3b36b106fa681659dc78b6e894a1965a7d93cae4..4644f75233eba22e88102f46f5799dc6ef3bf76c 100644
--- a/media/audio/audio_manager_base.cc
+++ b/media/audio/audio_manager_base.cc
@@ -8,6 +8,7 @@
 #include "base/bind_helpers.h"
 #include "base/command_line.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
 #include "build/build_config.h"
 #include "media/audio/audio_output_dispatcher_impl.h"
 #include "media/audio/audio_output_proxy.h"
@@ -80,6 +81,7 @@ AudioManagerBase::AudioManagerBase(AudioLogFactory* audio_log_factory)
       // block the UI thread when swapping devices.
       output_listeners_(
           ObserverList<AudioDeviceListener>::NOTIFY_EXISTING_ONLY),
+      state_listeners_(ObserverList<StateChangeListener>::NOTIFY_EXISTING_ONLY),
       audio_thread_("AudioThread"),
       audio_log_factory_(audio_log_factory) {
 #if defined(OS_WIN)
@@ -187,27 +189,38 @@ AudioInputStream* AudioManagerBase::MakeAudioInputStream(
 
   if (!params.IsValid() || (params.channels() > kMaxInputChannels) ||
       device_id.empty()) {
-    DLOG(ERROR) << "Audio parameters are invalid for device " << device_id;
+    std::ostringstream oss;
+    oss << "MakeAudioInputStream => invalid parameters";
+    DLOG(ERROR) << oss;
+    NotifyAllStateChangeListeners(oss.str());
     return NULL;
   }
 
   if (num_input_streams_ >= max_num_input_streams_) {
-    DLOG(ERROR) << "Number of opened input audio streams "
-                << num_input_streams_
-                << " exceed the max allowed number " << max_num_input_streams_;
+    std::ostringstream oss;
+    oss << "MakeAudioInputStream => "
+        << "number of opened input audio streams " << num_input_streams_
+        << " exceed the max allowed number " << max_num_input_streams_;
+    DLOG(ERROR) << oss;
+    NotifyAllStateChangeListeners(oss.str());
     return NULL;
   }
 
   AudioInputStream* stream;
+  std::ostringstream oss;
+  oss << "MakeAudioInputStream(";
   switch (params.format()) {
     case AudioParameters::AUDIO_PCM_LINEAR:
       stream = MakeLinearInputStream(params, device_id);
+      oss << "AUDIO_PCM_LINEAR)";
       break;
     case AudioParameters::AUDIO_PCM_LOW_LATENCY:
       stream = MakeLowLatencyInputStream(params, device_id);
+      oss << "AUDIO_PCM_LOW_LATENCY)";
       break;
     case AudioParameters::AUDIO_FAKE:
       stream = FakeAudioInputStream::MakeFakeStream(this, params);
+      oss << "AUDIO_FAKE)";
       break;
     default:
       stream = NULL;
@@ -217,6 +230,8 @@ AudioInputStream* AudioManagerBase::MakeAudioInputStream(
   if (stream) {
     ++num_input_streams_;
   }
+  oss << " => num_input_streams = " << num_input_streams_;
+  NotifyAllStateChangeListeners(oss.str());
 
   return stream;
 }
@@ -315,6 +330,9 @@ void AudioManagerBase::ReleaseInputStream(AudioInputStream* stream) {
   DCHECK(stream);
   // TODO(xians) : Have a clearer destruction path for the AudioInputStream.
   --num_input_streams_;
+  std::string log_string = base::StringPrintf(
+      "ReleaseInputStream => num_input_streams = %d", num_input_streams_);
+  NotifyAllStateChangeListeners(log_string);
   delete stream;
 }
 
@@ -358,6 +376,25 @@ void AudioManagerBase::NotifyAllOutputDeviceChangeListeners() {
   FOR_EACH_OBSERVER(AudioDeviceListener, output_listeners_, OnDeviceChange());
 }
 
+void AudioManagerBase::AddStateChangeListener(StateChangeListener* listener) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  state_listeners_.AddObserver(listener);
+}
+
+void AudioManagerBase::RemoveStateChangeListener(
+    StateChangeListener* listener) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  state_listeners_.RemoveObserver(listener);
+}
+
+void AudioManagerBase::NotifyAllStateChangeListeners(const std::string& msg) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+  std::string log_string("AMB::");
+  log_string += msg;
+  FOR_EACH_OBSERVER(
+      StateChangeListener, state_listeners_, OnStateChange(log_string));
+}
+
 AudioParameters AudioManagerBase::GetDefaultOutputStreamParameters() {
   return GetPreferredOutputStreamParameters(GetDefaultOutputDeviceID(),
       AudioParameters());