Implement native speech recognition for the launcher.

chrome/browser/ui/app_list/speech_recognizer.cc

+// Copyright 2014 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.
+
+#include "chrome/browser/ui/app_list/speech_recognizer.h"
+
+#include <algorithm>
+
+#include "base/bind.h"
+#include "base/strings/string16.h"
+#include "chrome/browser/ui/app_list/speech_recognizer_delegate.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/render_process_host.h"
+#include "content/public/browser/speech_recognition_manager.h"
+#include "content/public/browser/speech_recognition_session_config.h"
+#include "content/public/browser/web_contents.h"
+#include "content/public/common/speech_recognition_error.h"
+
+namespace app_list {
+
+// 5 second timeout to cancel if there's no speech heard.

[Matt Giuca, 2014/11/03 02:35:52]

"// Length of timeout ..." (don't include the value in the documentation).

[Anand Mistry (off Chromium), 2014/11/03 06:51:55]

Done.

+static const int kNoSpeechTimeoutInSeconds = 5;
+
+SpeechRecognizer::SpeechRecognizer(
+    SpeechRecognizerDelegate* delegate,
+    net::URLRequestContextGetter* url_request_context_getter,
+    const std::string& locale)
+    : delegate_(delegate),
+      url_request_context_getter_(url_request_context_getter),
+      locale_(locale),
+      speech_timeout_(false, false),
+      session_(-1),
+      weak_factory_(this) {
+}
+
+SpeechRecognizer::~SpeechRecognizer() {
+}
+
+void SpeechRecognizer::Start() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  // The speech recognizer checks to see if the request is allowed by looking
+  // up the renderer process. A renderer containing the app-list is hard-coded
+  // to be allowed.
+  content::WebContents* contents = delegate_->GetSpeechContents();
+  if (!contents)
+    return;
+
+  content::BrowserThread::PostTask(
+      content::BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&SpeechRecognizer::StartOnIOThread,
+                 this,
+                 contents->GetRenderProcessHost()->GetID(),
+                 url_request_context_getter_));
+}
+
+void SpeechRecognizer::StartOnIOThread(
+    int render_process_id,
+    scoped_refptr<net::URLRequestContextGetter> url_request_context_getter) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
+  if (session_ != -1)
+    StopOnIOThread();
+
+  content::SpeechRecognitionSessionConfig config;
+  config.language = locale_;
+  config.is_legacy_api = false;
+  config.continuous = true;
+  config.interim_results = true;
+  config.max_hypotheses = 1;
+  config.filter_profanities = true;
+  config.url_request_context_getter = url_request_context_getter;
+  config.event_listener = weak_factory_.GetWeakPtr();
+  config.initial_context.render_process_id = render_process_id;
+
+  auto speech_instance = content::SpeechRecognitionManager::GetInstance();
+  session_ = speech_instance->CreateSession(config);
+  speech_instance->StartSession(session_);
+}
+
+void SpeechRecognizer::Stop() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  content::BrowserThread::PostTask(
+      content::BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&SpeechRecognizer::StopOnIOThread, this));
+}
+
+void SpeechRecognizer::StopOnIOThread() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
+  if (session_ == -1)
+    return;
+
+  // Prevent recursion.
+  int session = session_;
+  session_ = -1;
+  StopSpeechTimeout();
+  content::SpeechRecognitionManager::GetInstance()->StopAudioCaptureForSession(
+      session);
+}
+
+void SpeechRecognizer::NotifyRecognitionStateChanged(
+    SpeechRecognitionState new_state) {
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(&SpeechRecognizerDelegate::OnSpeechRecognitionStateChanged,
+                 base::Unretained(delegate_),
+                 new_state));
+}
+
+void SpeechRecognizer::StartSpeechTimeout() {
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(&base::Timer::Start,
+                 base::Unretained(&speech_timeout_),
+                 FROM_HERE,
+                 base::TimeDelta::FromSeconds(kNoSpeechTimeoutInSeconds),
+                 base::Bind(&SpeechRecognizer::SpeechTimeout, this)));
+}
+
+void SpeechRecognizer::StopSpeechTimeout() {
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(&base::Timer::Stop,
+                 base::Unretained(&speech_timeout_)));
+}
+
+void SpeechRecognizer::SpeechTimeout() {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+  Stop();
+}
+
+void SpeechRecognizer::OnRecognitionStart(int session_id) {
+  NotifyRecognitionStateChanged(SPEECH_RECOGNITION_RECOGNIZING);
+}
+
+void SpeechRecognizer::OnRecognitionEnd(int session_id) {
+  StopOnIOThread();
+  NotifyRecognitionStateChanged(SPEECH_RECOGNITION_READY);
+}
+
+void SpeechRecognizer::OnRecognitionResults(
+    int session_id, const content::SpeechRecognitionResults& results) {
+  base::string16 result_str;
+  size_t final_count = 0;
+  for (const auto& result : results) {
+    if (!result.is_provisional)
+      final_count++;
+    result_str += result.hypotheses[0].utterance;
+  }
+  StopSpeechTimeout();
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(&SpeechRecognizerDelegate::OnSpeechResult,
+                 base::Unretained(delegate_),
+                 result_str,
+                 final_count == results.size()));
+
+  // Stop the moment we have a final result.
+  if (final_count == results.size())
+    StopOnIOThread();
+}
+
+void SpeechRecognizer::OnRecognitionError(
+    int session_id, const content::SpeechRecognitionError& error) {
+  StopOnIOThread();
+  if (error.code == content::SPEECH_RECOGNITION_ERROR_NETWORK) {
+    NotifyRecognitionStateChanged(SPEECH_RECOGNITION_NETWORK_ERROR);
+  }
+  NotifyRecognitionStateChanged(SPEECH_RECOGNITION_READY);
+}
+
+void SpeechRecognizer::OnSoundStart(int session_id) {
+  StartSpeechTimeout();
+  NotifyRecognitionStateChanged(SPEECH_RECOGNITION_IN_SPEECH);
+}
+
+void SpeechRecognizer::OnSoundEnd(int session_id) {
+  StopOnIOThread();
+  NotifyRecognitionStateChanged(SPEECH_RECOGNITION_RECOGNIZING);
+}
+
+void SpeechRecognizer::OnAudioLevelsChange(
+    int session_id, float volume, float noise_volume) {
+  volume = std::max(0.0f, volume - noise_volume);
+  // Both |volume| and |noise_volume| are defined to be in the range [0.0, 1.0].
+  // See: content/public/browser/speech_recognition_event_listener.h
+  int16_t sound_level = static_cast<int16_t>(INT16_MAX * volume);
+  content::BrowserThread::PostTask(
+      content::BrowserThread::UI,
+      FROM_HERE,
+      base::Bind(&SpeechRecognizerDelegate::OnSpeechSoundLevelChanged,
+                 base::Unretained(delegate_),
+                 sound_level));
+}
+
+void SpeechRecognizer::OnEnvironmentEstimationComplete(int session_id) {
+}
+
+void SpeechRecognizer::OnAudioStart(int session_id) {
+}
+
+void SpeechRecognizer::OnAudioEnd(int session_id) {
+}
+
+}  // namespace app_list