Speech refactoring: Reimplemented SpeechRecognitionManagerImpl as a FSM. (CL1.7)

content/browser/speech/speech_recognition_manager_impl.cc

Index: content/browser/speech/speech_recognition_manager_impl.cc
diff --git a/content/browser/speech/speech_recognition_manager_impl.cc b/content/browser/speech/speech_recognition_manager_impl.cc
index ed567e1996903a9ccaecc6e84df97095d1fc9163..c0f36e70ce3d3145be4b08590051e3ae9772bf35 100644
--- a/content/browser/speech/speech_recognition_manager_impl.cc
+++ b/content/browser/speech/speech_recognition_manager_impl.cc
@@ -5,361 +5,636 @@
 #include "content/browser/speech/speech_recognition_manager_impl.h"
 
 #include "base/bind.h"
+#include "base/memory/singleton.h"
 #include "content/browser/browser_main_loop.h"
-#include "content/browser/renderer_host/render_view_host_impl.h"
-#include "content/browser/speech/input_tag_speech_dispatcher_host.h"
+#include "content/browser/speech/google_one_shot_remote_engine.h"
+#include "content/browser/speech/speech_recognition_engine.h"
+#include "content/browser/speech/speech_recognizer_impl.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/browser/content_browser_client.h"
-#include "content/public/browser/speech_recognizer.h"
-#include "content/public/browser/render_view_host_delegate.h"
 #include "content/public/browser/resource_context.h"
+#include "content/public/browser/speech_recognition_event_listener.h"
 #include "content/public/browser/speech_recognition_manager_delegate.h"
-#include "content/public/browser/speech_recognition_preferences.h"
-#include "content/public/common/view_type.h"
+#include "content/public/browser/speech_recognition_session_config.h"
+#include "content/public/browser/speech_recognition_session_context.h"
+#include "content/public/common/speech_recognition_result.h"
 #include "media/audio/audio_manager.h"
 
+using base::Callback;
+using base::Unretained;
 using content::BrowserMainLoop;
 using content::BrowserThread;
-using content::RenderViewHostImpl;
+using content::SpeechRecognitionError;
+using content::SpeechRecognitionEventListener;
 using content::SpeechRecognitionManager;
-using content::SpeechRecognitionManagerDelegate;
+using content::SpeechRecognitionResult;
+using content::SpeechRecognitionSessionContext;
+using content::SpeechRecognitionSessionConfig;
+
+namespace {
+
+// A dummy implementation of the SpeechRecognitionManagerDelegate interface
+// used when no delegate has been passed to the SpeechRecognitionManagerImpl.
+class VoidRecognitionManagerDelegate :

[jam, 2012/04/24 15:56:32]

the convention we have for other delegates is to null check. i think given this
boilerplate that you have to add otherwise, it's not more work to null check

[Primiano Tucci (use gerrit), 2012/04/25 11:30:03]

I thought it was more efficient and "robust" (no need to remember the check) for
future changes.
Switched back to "if" checks.

+    public content::SpeechRecognitionManagerDelegate {
+ public:
+  static VoidRecognitionManagerDelegate* GetInstance() {
+    return Singleton<VoidRecognitionManagerDelegate>::get();
+  }
+  virtual void GetDiagnosticInformation(
+      bool* can_report_metrics, std::string* request_info) OVERRIDE {}
+  virtual bool IsRecognitionAllowed(int session_id) OVERRIDE { return false; }
+  virtual void ShowRecognitionRequested(int session_id) OVERRIDE {}
+  virtual void ShowWarmUp(int session_id) OVERRIDE {}
+  virtual void ShowRecognizing(int session_id) OVERRIDE {}
+  virtual void ShowRecording(int session_id) OVERRIDE {}
+  virtual void ShowInputVolume(
+      int session_id, float volume, float noise_volume) OVERRIDE {}
+  virtual void ShowError(int session_id,
+      const content::SpeechRecognitionError& error) OVERRIDE {}
+  virtual void DoClose(int session_id) OVERRIDE {}
+
+ private:
+  VoidRecognitionManagerDelegate() {}
+  virtual ~VoidRecognitionManagerDelegate() {}
+  friend struct DefaultSingletonTraits<VoidRecognitionManagerDelegate>;
+};
+
+}  // namespace
+
+namespace content {
+const int SpeechRecognitionManager::kSessionIDInvalid = 0;
 
 SpeechRecognitionManager* SpeechRecognitionManager::GetInstance() {
   return speech::SpeechRecognitionManagerImpl::GetInstance();
 }
+}  // namespace content
 
 namespace speech {
 
-struct SpeechRecognitionManagerImpl::SpeechRecognitionParams {
-  SpeechRecognitionParams(
-      InputTagSpeechDispatcherHost* delegate,
-      int session_id,
-      int render_process_id,
-      int render_view_id,
-      const gfx::Rect& element_rect,
-      const std::string& language,
-      const std::string& grammar,
-      const std::string& origin_url,
-      net::URLRequestContextGetter* context_getter,
-      content::SpeechRecognitionPreferences* recognition_prefs)
-      : delegate(delegate),
-        session_id(session_id),
-        render_process_id(render_process_id),
-        render_view_id(render_view_id),
-        element_rect(element_rect),
-        language(language),
-        grammar(grammar),
-        origin_url(origin_url),
-        context_getter(context_getter),
-        recognition_prefs(recognition_prefs) {
-  }
-
-  InputTagSpeechDispatcherHost* delegate;
-  int session_id;
-  int render_process_id;
-  int render_view_id;
-  gfx::Rect element_rect;
-  std::string language;
-  std::string grammar;
-  std::string origin_url;
-  net::URLRequestContextGetter* context_getter;
-  content::SpeechRecognitionPreferences* recognition_prefs;
-};
-
 SpeechRecognitionManagerImpl* SpeechRecognitionManagerImpl::GetInstance() {
   return Singleton<SpeechRecognitionManagerImpl>::get();
 }
 
 SpeechRecognitionManagerImpl::SpeechRecognitionManagerImpl()
-    : can_report_metrics_(false),
-      recording_session_id_(0) {
-  delegate_.reset(content::GetContentClient()->browser()->
-                  GetSpeechRecognitionManagerDelegate());
+    : interactive_session_id_(kSessionIDInvalid),
+      last_session_id_(kSessionIDInvalid),
+      is_dispatching_event_(false) {
+  delegate_ = content::GetContentClient()->browser()->
+      GetSpeechRecognitionManagerDelegate();
+  // In lack of one being provided, instantiate a void delegate so we can avoid
+  // unaesthetic "if (delegate_ != NULL)" statements.
+  if (delegate_ == NULL)
+    delegate_ = VoidRecognitionManagerDelegate::GetInstance();
 }
 
 SpeechRecognitionManagerImpl::~SpeechRecognitionManagerImpl() {
-  while (requests_.begin() != requests_.end())
-    CancelRecognition(requests_.begin()->first);
+  // Recognition sessions will be aborted by the corresponding destructors.
+  sessions_.clear();
 }
 
-bool SpeechRecognitionManagerImpl::HasAudioInputDevices() {
-  return BrowserMainLoop::GetAudioManager()->HasAudioInputDevices();
-}
+int SpeechRecognitionManagerImpl::CreateSession(
+    const SpeechRecognitionSessionConfig& config,
+    SpeechRecognitionEventListener* event_listener) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
 
-bool SpeechRecognitionManagerImpl::IsCapturingAudio() {
-  return BrowserMainLoop::GetAudioManager()->IsRecordingInProcess();
-}
+  const int session_id = GetNextSessionID();
+  DCHECK(!SessionExists(session_id));
+  // Set-up the new session.
+  Session& session = sessions_[session_id];
+  session.id = session_id;
+  session.event_listener = event_listener;
+  session.context = config.initial_context;
+
+  // TODO(primiano) Is this check enough just on creation or shall we move/copy
+  // it on SessionStart in order to repeat the check every time?
+  if (!delegate_->IsRecognitionAllowed(session_id)) {
+    sessions_.erase(session_id);
+    return kSessionIDInvalid;
+  }
 
-string16 SpeechRecognitionManagerImpl::GetAudioInputDeviceModel() {
-  return BrowserMainLoop::GetAudioManager()->GetAudioInputDeviceModel();
-}
+  std::string hardware_info;
+  bool can_report_metrics;
+  delegate_->GetDiagnosticInformation(&can_report_metrics, &hardware_info);
 
-bool SpeechRecognitionManagerImpl::HasPendingRequest(int session_id) const {
-  return requests_.find(session_id) != requests_.end();
-}
+  GoogleOneShotRemoteEngineConfig remote_engine_config;
+  remote_engine_config.language = config.language;
+  remote_engine_config.grammar = config.grammar;
+  remote_engine_config.audio_sample_rate =
+      SpeechRecognizerImpl::kAudioSampleRate;
+  remote_engine_config.audio_num_bits_per_sample =
+     SpeechRecognizerImpl::kNumBitsPerAudioSample;
+  remote_engine_config.filter_profanities = config.filter_profanities;
+  remote_engine_config.hardware_info = hardware_info;
+  remote_engine_config.origin_url = can_report_metrics ? config.origin_url : "";
 
-InputTagSpeechDispatcherHost* SpeechRecognitionManagerImpl::GetDelegate(
-    int session_id) const {
-  return requests_.find(session_id)->second.delegate;
+  GoogleOneShotRemoteEngine* google_remote_engine =
+      new GoogleOneShotRemoteEngine(config.url_request_context_getter);
+  google_remote_engine->SetConfig(remote_engine_config);
+
+  session.recognizer = new SpeechRecognizerImpl(this,
+                                                session_id,
+                                                google_remote_engine);
+  return session_id;
 }
 
-void SpeechRecognitionManagerImpl::ShowAudioInputSettings() {
-  // Since AudioManager::ShowAudioInputSettings can potentially launch external
-  // processes, do that in the FILE thread to not block the calling threads.
-  if (!BrowserThread::CurrentlyOn(BrowserThread::FILE)) {
-    BrowserThread::PostTask(
-        BrowserThread::FILE, FROM_HERE,
-        base::Bind(&SpeechRecognitionManagerImpl::ShowAudioInputSettings,
-                   base::Unretained(this)));
-    return;
+void SpeechRecognitionManagerImpl::StartSession(int session_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(SessionExists(session_id));
+
+  // If there is another interactive session, send it to background.
+  if (interactive_session_id_ != kSessionIDInvalid &&
+      interactive_session_id_ != session_id) {
+     SendSessionToBackground(interactive_session_id_);
   }
 
-  media::AudioManager* audio_manager = BrowserMainLoop::GetAudioManager();
-  DCHECK(audio_manager->CanShowAudioInputSettings());
-  if (audio_manager->CanShowAudioInputSettings())
-    audio_manager->ShowAudioInputSettings();
+   BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+     base::Bind(&SpeechRecognitionManagerImpl::DispatchEvent, Unretained(this),
+                session_id, FSMEventArgs(EVENT_START)));
 }
 
-void SpeechRecognitionManagerImpl::StartRecognition(
-    InputTagSpeechDispatcherHost* delegate,
-    int session_id,
-    int render_process_id,
-    int render_view_id,
-    const gfx::Rect& element_rect,
-    const std::string& language,
-    const std::string& grammar,
-    const std::string& origin_url,
-    net::URLRequestContextGetter* context_getter,
-    content::SpeechRecognitionPreferences* recognition_prefs) {
+void SpeechRecognitionManagerImpl::AbortSession(int session_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  BrowserThread::PostTask(
-      BrowserThread::UI, FROM_HERE,
-      base::Bind(
-          &SpeechRecognitionManagerImpl::CheckRenderViewTypeAndStartRecognition,
-          base::Unretained(this),
-          SpeechRecognitionParams(
-              delegate, session_id, render_process_id, render_view_id,
-              element_rect, language, grammar, origin_url, context_getter,
-              recognition_prefs)));
-}
-
-void SpeechRecognitionManagerImpl::CheckRenderViewTypeAndStartRecognition(
-    const SpeechRecognitionParams& params) {
-  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
-
-  RenderViewHostImpl* render_view_host = RenderViewHostImpl::FromID(
-      params.render_process_id, params.render_view_id);
-  if (!render_view_host || !render_view_host->GetDelegate())
-    return;
+  DCHECK(SessionExists(session_id));
 
-  // For host delegates other than VIEW_TYPE_WEB_CONTENTS we can't reliably show
-  // a popup, including the speech input bubble. In these cases for privacy
-  // reasons we don't want to start recording if the user can't be properly
-  // notified. An example of this is trying to show the speech input bubble
-  // within an extension popup: http://crbug.com/92083. In these situations the
-  // speech input extension API should be used instead.
-  if (render_view_host->GetDelegate()->GetRenderViewType() ==
-      content::VIEW_TYPE_WEB_CONTENTS) {
-    BrowserThread::PostTask(
-        BrowserThread::IO, FROM_HERE,
-        base::Bind(&SpeechRecognitionManagerImpl::ProceedStartingRecognition,
-        base::Unretained(this), params));
-  }
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SpeechRecognitionManagerImpl::DispatchEvent, Unretained(this),
+                 session_id, FSMEventArgs(EVENT_ABORT)));
 }
 
-void SpeechRecognitionManagerImpl::ProceedStartingRecognition(
-    const SpeechRecognitionParams& params) {
+void SpeechRecognitionManagerImpl::StopAudioCaptureForSession(int session_id) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
-  DCHECK(!HasPendingRequest(params.session_id));
+  DCHECK(SessionExists(session_id));
 
-  if (delegate_.get()) {
-    delegate_->ShowRecognitionRequested(
-        params.session_id, params.render_process_id, params.render_view_id,
-        params.element_rect);
-    delegate_->GetRequestInfo(&can_report_metrics_, &request_info_);
-  }
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SpeechRecognitionManagerImpl::DispatchEvent, Unretained(this),
+                 session_id, FSMEventArgs(EVENT_STOP_CAPTURE)));
+}
 
-  Request* request = &requests_[params.session_id];
-  request->delegate = params.delegate;
-  request->recognizer = content::SpeechRecognizer::Create(
-      this, params.session_id, params.language, params.grammar,
-      params.context_getter, params.recognition_prefs->FilterProfanities(),
-      request_info_, can_report_metrics_ ? params.origin_url : "");
-  request->is_active = false;
+void SpeechRecognitionManagerImpl::SendSessionToBackground(int session_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  DCHECK(SessionExists(session_id));
 
-  StartRecognitionForRequest(params.session_id);
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+      base::Bind(&SpeechRecognitionManagerImpl::DispatchEvent, Unretained(this),
+                 session_id, FSMEventArgs(EVENT_SET_BACKGROUND)));
 }
 
-void SpeechRecognitionManagerImpl::StartRecognitionForRequest(int session_id) {
-  SpeechRecognizerMap::iterator request = requests_.find(session_id);
-  if (request == requests_.end()) {
-    NOTREACHED();
+// Here begins the SpeechRecognitionEventListener interface implementation,
+// which will simply relay the events to the proper listener registered for the
+// particular session (most likely InputTagSpeechDispatcherHost) and intercept
+// some of them to provide UI notifications.
+
+void SpeechRecognitionManagerImpl::OnRecognitionStart(int session_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!SessionExists(session_id))
     return;
-  }
 
-  // We should not currently be recording for the session.
-  CHECK(recording_session_id_ != session_id);
+  DCHECK_EQ(interactive_session_id_, session_id);
+  delegate_->ShowWarmUp(session_id);
+  GetListener(session_id)->OnRecognitionStart(session_id);
+}
 
-  // If we are currently recording audio for another session, abort it cleanly.
-  if (recording_session_id_)
-    CancelRecognitionAndInformDelegate(recording_session_id_);
-  recording_session_id_ = session_id;
-  requests_[session_id].is_active = true;
-  requests_[session_id].recognizer->StartRecognition();
-  if (delegate_.get())
-    delegate_->ShowWarmUp(session_id);
+void SpeechRecognitionManagerImpl::OnAudioStart(int session_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!SessionExists(session_id))
+    return;
+
+  DCHECK_EQ(interactive_session_id_, session_id);
+  delegate_->ShowRecording(session_id);
+  GetListener(session_id)->OnAudioStart(session_id);
 }
 
-void SpeechRecognitionManagerImpl::CancelRecognitionForRequest(int session_id) {
-  // Ignore if the session id was not in our active recognizers list because the
-  // user might have clicked more than once, or recognition could have been
-  // ended due to other reasons before the user click was processed.
-  if (!HasPendingRequest(session_id))
+void SpeechRecognitionManagerImpl::OnEnvironmentEstimationComplete(
+    int session_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!SessionExists(session_id))
     return;
 
-  CancelRecognitionAndInformDelegate(session_id);
+  DCHECK_EQ(interactive_session_id_, session_id);
+  GetListener(session_id)->OnEnvironmentEstimationComplete(session_id);
 }
 
-void SpeechRecognitionManagerImpl::FocusLostForRequest(int session_id) {
-  // See above comment.
-  if (!HasPendingRequest(session_id))
+void SpeechRecognitionManagerImpl::OnSoundStart(int session_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!SessionExists(session_id))
     return;
 
-  // If this is an ongoing recording or if we were displaying an error message
-  // to the user, abort it since user has switched focus. Otherwise
-  // recognition has started and keep that going so user can start speaking to
-  // another element while this gets the results in parallel.
-  if (recording_session_id_ == session_id || !requests_[session_id].is_active)
-    CancelRecognitionAndInformDelegate(session_id);
-}
-
-void SpeechRecognitionManagerImpl::CancelRecognition(int session_id) {
-  DCHECK(HasPendingRequest(session_id));
-  if (requests_[session_id].is_active)
-    requests_[session_id].recognizer->AbortRecognition();
-  requests_.erase(session_id);
-  if (recording_session_id_ == session_id)
-    recording_session_id_ = 0;
-  if (delegate_.get())
-    delegate_->DoClose(session_id);
-}
-
-void SpeechRecognitionManagerImpl::CancelAllRequestsWithDelegate(
-    InputTagSpeechDispatcherHost* delegate) {
-  SpeechRecognizerMap::iterator it = requests_.begin();
-  while (it != requests_.end()) {
-    if (it->second.delegate == delegate) {
-      CancelRecognition(it->first);
-      // This map will have very few elements so it is simpler to restart.
-      it = requests_.begin();
-    } else {
-      ++it;
-    }
-  }
+  DCHECK_EQ(interactive_session_id_, session_id);
+  GetListener(session_id)->OnSoundStart(session_id);
 }
 
-void SpeechRecognitionManagerImpl::StopRecording(int session_id) {
-  // No pending requests on extension popups.
-  if (!HasPendingRequest(session_id))
+void SpeechRecognitionManagerImpl::OnSoundEnd(int session_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!SessionExists(session_id))
     return;
 
-  requests_[session_id].recognizer->StopAudioCapture();
+  GetListener(session_id)->OnSoundEnd(session_id);
 }
 
-// -------- SpeechRecognitionEventListener interface implementation. ---------
+void SpeechRecognitionManagerImpl::OnAudioEnd(int session_id) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!SessionExists(session_id))
+    return;
+
+  // OnAudioEnd can also be raised after an abort request, when the session is
+  // not interactive anymore.
+  if (interactive_session_id_ == session_id)
+    delegate_->ShowRecognizing(session_id);
+
+  GetListener(session_id)->OnAudioEnd(session_id);
+}
 
 void SpeechRecognitionManagerImpl::OnRecognitionResult(
     int session_id, const content::SpeechRecognitionResult& result) {
-  DCHECK(HasPendingRequest(session_id));
-  GetDelegate(session_id)->SetRecognitionResult(session_id, result);
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!SessionExists(session_id))
+    return;
+
+  GetListener(session_id)->OnRecognitionResult(session_id, result);
+  FSMEventArgs event_args(EVENT_RECOGNITION_RESULT);
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+    base::Bind(&SpeechRecognitionManagerImpl::DispatchEvent, Unretained(this),
+               session_id, event_args));
 }
 
-void SpeechRecognitionManagerImpl::OnAudioEnd(int session_id) {
-  if (recording_session_id_ != session_id)
+void SpeechRecognitionManagerImpl::OnRecognitionError(
+    int session_id, const content::SpeechRecognitionError& error) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!SessionExists(session_id))
     return;
-  DCHECK_EQ(recording_session_id_, session_id);
-  DCHECK(HasPendingRequest(session_id));
-  if (!requests_[session_id].is_active)
+
+  GetListener(session_id)->OnRecognitionError(session_id, error);
+  FSMEventArgs event_args(EVENT_RECOGNITION_ERROR);
+  event_args.speech_error = error;
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+    base::Bind(&SpeechRecognitionManagerImpl::DispatchEvent, Unretained(this),
+               session_id, event_args));
+}
+
+void SpeechRecognitionManagerImpl::OnAudioLevelsChange(
+    int session_id, float volume, float noise_volume) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!SessionExists(session_id))
     return;
-  recording_session_id_ = 0;
-  GetDelegate(session_id)->DidCompleteRecording(session_id);
-  if (delegate_.get())
-    delegate_->ShowRecognizing(session_id);
+
+  delegate_->ShowInputVolume(session_id, volume, noise_volume);
+  GetListener(session_id)->OnAudioLevelsChange(session_id, volume,
+                                               noise_volume);
 }
 
 void SpeechRecognitionManagerImpl::OnRecognitionEnd(int session_id) {
-  if (!HasPendingRequest(session_id) || !requests_[session_id].is_active)
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!SessionExists(session_id))
     return;
-  GetDelegate(session_id)->DidCompleteRecognition(session_id);
-  requests_.erase(session_id);
-  if (delegate_.get())
-    delegate_->DoClose(session_id);
+
+  GetListener(session_id)->OnRecognitionEnd(session_id);
+  BrowserThread::PostTask(BrowserThread::IO, FROM_HERE,
+    base::Bind(&SpeechRecognitionManagerImpl::DispatchEvent, Unretained(this),
+               session_id, FSMEventArgs(EVENT_RECOGNITION_ENDED)));
 }
 
-void SpeechRecognitionManagerImpl::OnSoundStart(int session_id) {
+// TODO(primiano) After CL2: if we see that both InputTagDispatcherHost and
+// SpeechRecognitionDispatcherHost do the same lookup operations, implement the
+// lookup method directly here.
+int SpeechRecognitionManagerImpl::LookupSessionByContext(
+    Callback<bool(const SpeechRecognitionSessionContext&)> matcher) const {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  SessionsTable::const_iterator iter;
+  // Note: the callback (matcher) must NEVER perform non-const calls on us.
+  for(iter = sessions_.begin(); iter != sessions_.end(); ++iter) {
+    const int session_id = iter->first;
+    const Session& session = iter->second;
+    bool matches = matcher.Run(session.context);
+    if (matches)
+      return session_id;
+  }
+  return kSessionIDInvalid;
 }
 
-void SpeechRecognitionManagerImpl::OnSoundEnd(int session_id) {
+SpeechRecognitionSessionContext
+SpeechRecognitionManagerImpl::GetSessionContext(int session_id) const {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  SessionsTable::const_iterator iter = sessions_.find(session_id);
+  DCHECK(iter != sessions_.end());
+  return iter->second.context;
 }
 
-void SpeechRecognitionManagerImpl::OnRecognitionError(
-    int session_id, const content::SpeechRecognitionError& error) {
-  DCHECK(HasPendingRequest(session_id));
-  if (session_id == recording_session_id_)
-    recording_session_id_ = 0;
-  requests_[session_id].is_active = false;
-  if (delegate_.get()) {
-    if (error.code == content::SPEECH_RECOGNITION_ERROR_AUDIO &&
-        error.details == content::SPEECH_AUDIO_ERROR_DETAILS_NO_MIC) {
-      delegate_->ShowMicError(session_id,
-          SpeechRecognitionManagerDelegate::MIC_ERROR_NO_DEVICE_AVAILABLE);
-    } else if (error.code == content::SPEECH_RECOGNITION_ERROR_AUDIO &&
-               error.details == content::SPEECH_AUDIO_ERROR_DETAILS_IN_USE) {
-      delegate_->ShowMicError(session_id,
-          SpeechRecognitionManagerDelegate::MIC_ERROR_DEVICE_IN_USE);
-    } else {
-      delegate_->ShowRecognizerError(session_id, error.code);
-    }
+void SpeechRecognitionManagerImpl::AbortAllSessionsForListener(
+    SpeechRecognitionEventListener* listener) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  // AbortSession is asynchronous and the session will not be removed from the
+  // collection while we are iterating over it.
+  for (SessionsTable::iterator it = sessions_.begin(); it != sessions_.end();
+       ++it) {
+    if (it->second.event_listener == listener)
+      AbortSession(it->first);
   }
 }
 
-void SpeechRecognitionManagerImpl::OnAudioStart(int session_id) {
-  DCHECK(HasPendingRequest(session_id));
-  DCHECK_EQ(recording_session_id_, session_id);
-  if (delegate_.get())
-    delegate_->ShowRecording(session_id);
+// -----------------------  Core FSM implementation ---------------------------
+void SpeechRecognitionManagerImpl::DispatchEvent(int session_id,
+                                                 FSMEventArgs event_args) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::IO));
+  if (!SessionExists(session_id))
+    return;
+
+  Session& session = sessions_[session_id];
+  DCHECK_LE(session.state, STATE_MAX_VALUE);
+  DCHECK_LE(event_args.event, EVENT_MAX_VALUE);
+
+  // Event dispatching must be sequential, otherwise it will break all the rules
+  // and the assumptions of the finite state automata model.
+  DCHECK(!is_dispatching_event_);
+  is_dispatching_event_ = true;
+
+  // Pedantic preconditions consistency checks.
+  if (session.state == STATE_INTERACTIVE)
+    DCHECK_EQ(interactive_session_id_, session_id);
+
+  if (session.state == STATE_BACKGROUND ||
+      session.state == STATE_WAITING_FOR_DELETION) {
+    DCHECK_NE(interactive_session_id_, session_id);
+  }
+
+  session.state = ExecuteTransitionAndGetNextState(session, event_args);
+
+  is_dispatching_event_ = false;
+}
+
+// This FSM handles the evolution of each session, from the viewpoint of the
+// interaction with the user (that may be either the browser end-user which
+// interacts with UI bubbles, or JS developer intracting with JS methods).
+// All the events received by the SpeechRecognizerImpl instances (one for each
+// session) are always routed to the SpeechRecognitionEventListener(s)
+// regardless the choices taken in this FSM.
+SpeechRecognitionManagerImpl::FSMState
+SpeechRecognitionManagerImpl::ExecuteTransitionAndGetNextState(
+    Session& session, const FSMEventArgs& event_args) {
+  // Some notes for the code below:
+  // - A session can be deleted only if it is not active, thus only if it ended
+  //   spontaneously or we issued a prior SessionAbort. In these cases, we must
+  //   wait for a RECOGNITION_ENDED event (which is guaranteed to come always at
+  //   last by the SpeechRecognizer) in order to free resources gracefully.
+  // - Use SessionDelete only when absolutely sure that the recognizer is not
+  //   active. Prefer SessionAbort, which will do it gracefully, otherwise.
+  // - Since this class methods are publicly exported,  START, ABORT,
+  //   STOP_CAPTURE and SET_BACKGROUND events can arrive in every moment from
+  //   the outside wild wolrd, even if they make no sense.
+  const FSMEvent event = event_args.event;
+  switch (session.state) {
+    case STATE_IDLE:
+      // Session has just been created or had an error while interactive.
+      switch (event) {
+        case EVENT_START:
+          return SessionStart(session, event_args);
+        case EVENT_ABORT:
+        case EVENT_SET_BACKGROUND:
+          return SessionAbort(session, event_args);
+        case EVENT_STOP_CAPTURE:
+        case EVENT_RECOGNITION_ENDED:
+          // In case of error, we come back in this state before receiving the
+          // OnRecognitionEnd event, thus EVENT_RECOGNITION_ENDED is feasible.
+          return DoNothing(session, event_args);
+        case EVENT_RECOGNITION_RESULT:
+        case EVENT_RECOGNITION_ERROR:
+          return NotFeasible(session, event_args);
+      }
+      break;
+    case STATE_INTERACTIVE:
+      // The recognizer can be either capturing audio or waiting for a result.
+      switch (event) {
+        case EVENT_RECOGNITION_RESULT:
+          // TODO(primiano) Valid only in single shot mode. Review in next CLs.
+          return SessionSetBackground(session, event_args);
+        case EVENT_SET_BACKGROUND:
+          return SessionAbortIfCapturingAudioOrBackground(session, event_args);
+        case EVENT_STOP_CAPTURE:
+          return SessionStopAudioCapture(session, event_args);
+        case EVENT_ABORT:
+          return SessionAbort(session, event_args);
+        case EVENT_RECOGNITION_ERROR:
+          return SessionReportError(session, event_args);
+        case EVENT_RECOGNITION_ENDED:
+          // If we're still interactive it means that no result was received
+          // in the meanwhile (otherwise we'd have been sent to background).
+          return SessionReportNoMatch(session, event_args);
+        case EVENT_START:
+          return DoNothing(session, event_args);
+      }
+      break;
+    case STATE_BACKGROUND:
+      switch (event) {
+        case EVENT_ABORT:
+          return SessionAbort(session, event_args);
+        case EVENT_RECOGNITION_ENDED:
+          return SessionDelete(session, event_args);
+        case EVENT_START:
+        case EVENT_STOP_CAPTURE:
+        case EVENT_RECOGNITION_RESULT:
+        case EVENT_RECOGNITION_ERROR:
+          return DoNothing(session, event_args);
+        case EVENT_SET_BACKGROUND:
+          return NotFeasible(session, event_args);
+      }
+      break;
+    case STATE_WAITING_FOR_DELETION:
+      switch (event) {
+        case EVENT_RECOGNITION_ENDED:
+          return SessionDelete(session, event_args);
+        case EVENT_ABORT:
+        case EVENT_START:
+        case EVENT_STOP_CAPTURE:
+        case EVENT_SET_BACKGROUND:
+        case EVENT_RECOGNITION_RESULT:
+        case EVENT_RECOGNITION_ERROR:
+          return DoNothing(session, event_args);
+      }
+      break;
+  }
+  return NotFeasible(session, event_args);
+}
+
+// ----------- Contract for all the FSM evolution functions below -------------
+//  - Are guaranteed to be executed in the IO thread;
+//  - Are guaranteed to be not reentrant (themselves and each other);
+//  - event_args members are guaranteed to be stable during the call;
+
+SpeechRecognitionManagerImpl::FSMState
+SpeechRecognitionManagerImpl::SessionStart(Session& session,
+                                           const FSMEventArgs& event_args) {
+  if (interactive_session_id_ != kSessionIDInvalid)
+    delegate_->DoClose(interactive_session_id_);
+  interactive_session_id_ = session.id;
+  delegate_->ShowRecognitionRequested(session.id);
+  session.recognizer->StartRecognition();
+  return STATE_INTERACTIVE;
+}
+
+SpeechRecognitionManagerImpl::FSMState
+SpeechRecognitionManagerImpl::SessionAbort(Session& session,
+                                           const FSMEventArgs& event_args) {
+  if (interactive_session_id_ == session.id) {
+    interactive_session_id_ = kSessionIDInvalid;
+    delegate_->DoClose(session.id);
+  }
+
+  // If abort was requested while the recognizer was inactive, delete directly.
+  if (session.recognizer == NULL || !session.recognizer->IsActive())
+    return SessionDelete(session, event_args);
+
+  // Otherwise issue an abort and delete gracefully, waiting for a
+  // RECOGNITION_ENDED event first.
+  session.recognizer->AbortRecognition();
+  return STATE_WAITING_FOR_DELETION;
 }
 
-void SpeechRecognitionManagerImpl::OnRecognitionStart(int session_id) {
+SpeechRecognitionManagerImpl::FSMState
+SpeechRecognitionManagerImpl::SessionStopAudioCapture(
+    Session& session, const FSMEventArgs& event_args) {
+  DCHECK(session.recognizer != NULL);
+  DCHECK(session.recognizer->IsActive());
+  if (session.recognizer->IsCapturingAudio())
+    session.recognizer->StopAudioCapture();
+  return STATE_INTERACTIVE;
 }
 
-void SpeechRecognitionManagerImpl::OnEnvironmentEstimationComplete(
-    int session_id) {
-  DCHECK(HasPendingRequest(session_id));
-  DCHECK_EQ(recording_session_id_, session_id);
+SpeechRecognitionManagerImpl::FSMState
+SpeechRecognitionManagerImpl::SessionAbortIfCapturingAudioOrBackground(
+    Session& session, const FSMEventArgs& event_args) {
+  DCHECK_EQ(interactive_session_id_, session.id);
+
+  DCHECK(session.recognizer != NULL);
+  DCHECK(session.recognizer->IsActive());
+  if (session.recognizer->IsCapturingAudio())
+    return SessionAbort(session, event_args);
+
+  interactive_session_id_ = kSessionIDInvalid;
+  delegate_->DoClose(session.id);
+  return STATE_BACKGROUND;
 }
 
-void SpeechRecognitionManagerImpl::OnAudioLevelsChange(
-    int session_id, float volume, float noise_volume) {
-  DCHECK(HasPendingRequest(session_id));
-  DCHECK_EQ(recording_session_id_, session_id);
-  if (delegate_.get())
-    delegate_->ShowInputVolume(session_id, volume, noise_volume);
+
+SpeechRecognitionManagerImpl::FSMState
+SpeechRecognitionManagerImpl::SessionSetBackground(
+    Session& session, const FSMEventArgs& event_args) {
+  DCHECK_EQ(interactive_session_id_, session.id);
+  interactive_session_id_ = kSessionIDInvalid;
+  delegate_->DoClose(session.id);
+  return STATE_BACKGROUND;
 }
 
-void SpeechRecognitionManagerImpl::CancelRecognitionAndInformDelegate(
-    int session_id) {
-  InputTagSpeechDispatcherHost* cur_delegate = GetDelegate(session_id);
-  CancelRecognition(session_id);
-  cur_delegate->DidCompleteRecording(session_id);
-  cur_delegate->DidCompleteRecognition(session_id);
+SpeechRecognitionManagerImpl::FSMState
+SpeechRecognitionManagerImpl::SessionReportError(
+    Session& session, const FSMEventArgs& event_args) {
+  DCHECK_EQ(interactive_session_id_, session.id);
+  delegate_->ShowError(session.id, event_args.speech_error);
+  return STATE_IDLE;
+}
+
+SpeechRecognitionManagerImpl::FSMState
+SpeechRecognitionManagerImpl::SessionReportNoMatch(
+    Session& session, const FSMEventArgs& event_args) {
+  DCHECK_EQ(interactive_session_id_, session.id);
+  delegate_->ShowError(
+      session.id,
+      SpeechRecognitionError(content::SPEECH_RECOGNITION_ERROR_NO_MATCH));
+  return STATE_IDLE;
+}
+
+SpeechRecognitionManagerImpl::FSMState
+SpeechRecognitionManagerImpl::SessionDelete(Session& session,
+                                            const FSMEventArgs& event_args) {
+  DCHECK(session.recognizer == NULL || !session.recognizer->IsActive());
+  if (interactive_session_id_ == session.id) {
+    interactive_session_id_ = kSessionIDInvalid;
+    delegate_->DoClose(session.id);
+  }
+  sessions_.erase(session.id);
+  // Next state is irrelevant, the session will be deleted afterwards.
+  return STATE_WAITING_FOR_DELETION;
+}
+
+SpeechRecognitionManagerImpl::FSMState
+SpeechRecognitionManagerImpl::DoNothing(Session& session,
+                                        const FSMEventArgs& event_args) {
+  return session.state;
+}
+
+SpeechRecognitionManagerImpl::FSMState
+SpeechRecognitionManagerImpl::NotFeasible(Session& session,
+                                          const FSMEventArgs& event_args) {
+  NOTREACHED() << "Unfeasible event " << event_args.event
+               << " in state " << session.state
+               << " for session " << session.id;
+  return session.state;
+}
+
+int SpeechRecognitionManagerImpl::GetNextSessionID() {
+  ++last_session_id_;
+  // Deal with wrapping of last_session_id_. (How civilized).
+  if (last_session_id_ <= 0)
+    last_session_id_ = 1;
+  return last_session_id_;
+}
+
+bool SpeechRecognitionManagerImpl::SessionExists(int session_id) const {
+  return sessions_.find(session_id) != sessions_.end();
+}
+
+SpeechRecognitionEventListener* SpeechRecognitionManagerImpl::GetListener(
+    int session_id) const {
+  SessionsTable::const_iterator iter = sessions_.find(session_id);
+  DCHECK(iter != sessions_.end());
+  return iter->second.event_listener;
+}
+
+
+bool SpeechRecognitionManagerImpl::HasAudioInputDevices() {
+  return BrowserMainLoop::GetAudioManager()->HasAudioInputDevices();
+}
+
+bool SpeechRecognitionManagerImpl::IsCapturingAudio() {
+  return BrowserMainLoop::GetAudioManager()->IsRecordingInProcess();
+}
+
+string16 SpeechRecognitionManagerImpl::GetAudioInputDeviceModel() {
+  return BrowserMainLoop::GetAudioManager()->GetAudioInputDeviceModel();
+}
+
+void SpeechRecognitionManagerImpl::ShowAudioInputSettings() {
+  // Since AudioManager::ShowAudioInputSettings can potentially launch external
+  // processes, do that in the FILE thread to not block the calling threads.
+  if (!BrowserThread::CurrentlyOn(BrowserThread::FILE)) {
+    BrowserThread::PostTask(
+        BrowserThread::FILE, FROM_HERE,
+        base::Bind(&SpeechRecognitionManagerImpl::ShowAudioInputSettings,
+                   base::Unretained(this)));
+    return;
+  }
+
+  media::AudioManager* audio_manager = BrowserMainLoop::GetAudioManager();
+  DCHECK(audio_manager->CanShowAudioInputSettings());
+  if (audio_manager->CanShowAudioInputSettings())
+    audio_manager->ShowAudioInputSettings();
+}
+
+SpeechRecognitionManagerImpl::FSMEventArgs::FSMEventArgs(FSMEvent event_value)
+  : event(event_value),
+    speech_error(content::SPEECH_RECOGNITION_ERROR_NONE) {
+}
+
+SpeechRecognitionManagerImpl::FSMEventArgs::~FSMEventArgs() {
 }
 
-SpeechRecognitionManagerImpl::Request::Request()
-    : is_active(false) {
+SpeechRecognitionManagerImpl::Session::Session()
+  : id(kSessionIDInvalid),
+    event_listener(NULL),
+    state(STATE_IDLE) {
 }
 
-SpeechRecognitionManagerImpl::Request::~Request() {
+SpeechRecognitionManagerImpl::Session::~Session() {
 }
 
 }  // namespace speech