Devirtualize SpeechRecognitionEngine

content/browser/speech/speech_recognition_engine.cc

Index: content/browser/speech/speech_recognition_engine.cc
diff --git a/content/browser/speech/speech_recognition_engine.cc b/content/browser/speech/speech_recognition_engine.cc
index e3b236b79760d3c27632462189b7b97b8ed8aa47..b0fac7db62feb1ea375d7c2772dd53e7ec85d8c3 100644
--- a/content/browser/speech/speech_recognition_engine.cc
+++ b/content/browser/speech/speech_recognition_engine.cc
@@ -4,13 +4,77 @@
 
 #include "content/browser/speech/speech_recognition_engine.h"
 
+#include <algorithm>
+#include <vector>
+
+#include "base/big_endian.h"
+#include "base/bind.h"
+#include "base/rand_util.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "base/strings/utf_string_conversions.h"
+#include "base/time/time.h"
+#include "content/browser/speech/audio_buffer.h"
+#include "content/browser/speech/proto/google_streaming_api.pb.h"
+#include "content/public/common/speech_recognition_error.h"
+#include "content/public/common/speech_recognition_result.h"
+#include "google_apis/google_api_keys.h"
+#include "net/base/escape.h"
+#include "net/base/load_flags.h"
+#include "net/url_request/http_user_agent_settings.h"
+#include "net/url_request/url_fetcher.h"
+#include "net/url_request/url_request_context.h"
+#include "net/url_request/url_request_context_getter.h"
+#include "net/url_request/url_request_status.h"
+
+using net::URLFetcher;
+
+namespace content {
 namespace {
+
+const char kWebServiceBaseUrl[] =
+    "https://www.google.com/speech-api/full-duplex/v1";
+const char kDownstreamUrl[] = "/down?";
+const char kUpstreamUrl[] = "/up?";
+
+// This matches the maximum maxAlternatives value supported by the server.
+const uint32_t kMaxMaxAlternatives = 30;
+
+// TODO(hans): Remove this and other logging when we don't need it anymore.
+void DumpResponse(const std::string& response) {
+  DVLOG(1) << "------------";
+  proto::SpeechRecognitionEvent event;
+  if (!event.ParseFromString(response)) {
+    DVLOG(1) << "Parse failed!";
+    return;
+  }
+  if (event.has_status())
+    DVLOG(1) << "STATUS\t" << event.status();
+  if (event.has_endpoint())
+    DVLOG(1) << "ENDPOINT\t" << event.endpoint();
+  for (int i = 0; i < event.result_size(); ++i) {
+    DVLOG(1) << "RESULT #" << i << ":";
+    const proto::SpeechRecognitionResult& res = event.result(i);
+    if (res.has_final())
+      DVLOG(1) << "  final:\t" << res.final();
+    if (res.has_stability())
+      DVLOG(1) << "  STABILITY:\t" << res.stability();
+    for (int j = 0; j < res.alternative_size(); ++j) {
+      const proto::SpeechRecognitionAlternative& alt =
+          res.alternative(j);
+      if (alt.has_confidence())
+        DVLOG(1) << "    CONFIDENCE:\t" << alt.confidence();
+      if (alt.has_transcript())
+        DVLOG(1) << "    TRANSCRIPT:\t" << alt.transcript();
+    }
+  }
+}
+
 const int kDefaultConfigSampleRate = 8000;
 const int kDefaultConfigBitsPerSample = 16;
 const uint32_t kDefaultMaxHypotheses = 1;
-}  // namespace
 
-namespace content {
+}  // namespace
 
 SpeechRecognitionEngine::Config::Config()
     : filter_profanities(false),
@@ -18,10 +82,574 @@ SpeechRecognitionEngine::Config::Config()
       interim_results(true),
       max_hypotheses(kDefaultMaxHypotheses),
       audio_sample_rate(kDefaultConfigSampleRate),
-      audio_num_bits_per_sample(kDefaultConfigBitsPerSample) {
+      audio_num_bits_per_sample(kDefaultConfigBitsPerSample) {}
+
+SpeechRecognitionEngine::Config::~Config() {}
+
+const int SpeechRecognitionEngine::kAudioPacketIntervalMs = 100;
+const int SpeechRecognitionEngine::kUpstreamUrlFetcherIdForTesting = 0;
+const int SpeechRecognitionEngine::kDownstreamUrlFetcherIdForTesting = 1;
+const int SpeechRecognitionEngine::kWebserviceStatusNoError = 0;
+const int SpeechRecognitionEngine::kWebserviceStatusErrorNoMatch = 5;
+
+SpeechRecognitionEngine::SpeechRecognitionEngine(
+    net::URLRequestContextGetter* context)
+    : url_context_(context),
+      previous_response_length_(0),
+      got_last_definitive_result_(false),
+      is_dispatching_event_(false),
+      use_framed_post_data_(false),
+      state_(STATE_IDLE) {}
+
+SpeechRecognitionEngine::~SpeechRecognitionEngine() {}
+
+void SpeechRecognitionEngine::SetConfig(const Config& config) {
+  config_ = config;
+}
+
+void SpeechRecognitionEngine::StartRecognition() {
+  FSMEventArgs event_args(EVENT_START_RECOGNITION);
+  DispatchEvent(event_args);
+}
+
+void SpeechRecognitionEngine::EndRecognition() {
+  FSMEventArgs event_args(EVENT_END_RECOGNITION);
+  DispatchEvent(event_args);
+}
+
+void SpeechRecognitionEngine::TakeAudioChunk(const AudioChunk& data) {
+  FSMEventArgs event_args(EVENT_AUDIO_CHUNK);
+  event_args.audio_data = &data;
+  DispatchEvent(event_args);
+}
+
+void SpeechRecognitionEngine::AudioChunksEnded() {
+  FSMEventArgs event_args(EVENT_AUDIO_CHUNKS_ENDED);
+  DispatchEvent(event_args);
+}
+
+void SpeechRecognitionEngine::OnURLFetchComplete(const URLFetcher* source) {
+  const bool kResponseComplete = true;
+  DispatchHTTPResponse(source, kResponseComplete);
+}
+
+void SpeechRecognitionEngine::OnURLFetchDownloadProgress(
+    const URLFetcher* source,
+    int64_t current,
+    int64_t total) {
+  const bool kPartialResponse = false;
+  DispatchHTTPResponse(source, kPartialResponse);
+}
+
+void SpeechRecognitionEngine::DispatchHTTPResponse(const URLFetcher* source,
+                                                   bool end_of_response) {
+  DCHECK(CalledOnValidThread());
+  DCHECK(source);
+  const bool response_is_good = source->GetStatus().is_success() &&
+                                source->GetResponseCode() == 200;
+  std::string response;
+  if (response_is_good)
+    source->GetResponseAsString(&response);
+  const size_t current_response_length = response.size();
+
+  DVLOG(1) << (source == downstream_fetcher_.get() ? "Downstream" : "Upstream")
+           << "HTTP, code: " << source->GetResponseCode()
+           << "      length: " << current_response_length
+           << "      eor: " << end_of_response;
+
+  // URLFetcher provides always the entire response buffer, but we are only
+  // interested in the fresh data introduced by the last chunk. Therefore, we
+  // drop the previous content we have already processed.
+  if (current_response_length != 0) {
+    DCHECK_GE(current_response_length, previous_response_length_);
+    response.erase(0, previous_response_length_);
+    previous_response_length_ = current_response_length;
+  }
+
+  if (!response_is_good && source == downstream_fetcher_.get()) {
+    DVLOG(1) << "Downstream error " << source->GetResponseCode();
+    FSMEventArgs event_args(EVENT_DOWNSTREAM_ERROR);
+    DispatchEvent(event_args);
+    return;
+  }
+  if (!response_is_good && source == upstream_fetcher_.get()) {
+    DVLOG(1) << "Upstream error " << source->GetResponseCode()
+             << " EOR " << end_of_response;
+    FSMEventArgs event_args(EVENT_UPSTREAM_ERROR);
+    DispatchEvent(event_args);
+    return;
+  }
+
+  // Ignore incoming data on the upstream connection.
+  if (source == upstream_fetcher_.get())
+    return;
+
+  DCHECK(response_is_good && source == downstream_fetcher_.get());
+
+  // The downstream response is organized in chunks, whose size is determined
+  // by a 4 bytes prefix, transparently handled by the ChunkedByteBuffer class.
+  // Such chunks are sent by the speech recognition webservice over the HTTP
+  // downstream channel using HTTP chunked transfer (unrelated to our chunks).
+  // This function is called every time an HTTP chunk is received by the
+  // url fetcher. However there isn't any particular matching beween our
+  // protocol chunks and HTTP chunks, in the sense that a single HTTP chunk can
+  // contain a portion of one chunk or even more chunks together.
+  chunked_byte_buffer_.Append(response);
+
+  // A single HTTP chunk can contain more than one data chunk, thus the while.
+  while (chunked_byte_buffer_.HasChunks()) {
+    FSMEventArgs event_args(EVENT_DOWNSTREAM_RESPONSE);
+    event_args.response = chunked_byte_buffer_.PopChunk();
+    DCHECK(event_args.response.get());
+    DumpResponse(std::string(event_args.response->begin(),
+                             event_args.response->end()));
+    DispatchEvent(event_args);
+  }
+  if (end_of_response) {
+    FSMEventArgs event_args(EVENT_DOWNSTREAM_CLOSED);
+    DispatchEvent(event_args);
+  }
+}
+
+bool SpeechRecognitionEngine::IsRecognitionPending() const {
+  DCHECK(CalledOnValidThread());
+  return state_ != STATE_IDLE;
+}
+
+int SpeechRecognitionEngine::GetDesiredAudioChunkDurationMs() const {
+  return kAudioPacketIntervalMs;
+}
+
+// -----------------------  Core FSM implementation ---------------------------
+
+void SpeechRecognitionEngine::DispatchEvent(
+    const FSMEventArgs& event_args) {
+  DCHECK(CalledOnValidThread());
+  DCHECK_LE(event_args.event, EVENT_MAX_VALUE);
+  DCHECK_LE(state_, STATE_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;
+
+  state_ = ExecuteTransitionAndGetNextState(event_args);
+
+  is_dispatching_event_ = false;
+}
+
+SpeechRecognitionEngine::FSMState
+SpeechRecognitionEngine::ExecuteTransitionAndGetNextState(
+    const FSMEventArgs& event_args) {
+  const FSMEvent event = event_args.event;
+  switch (state_) {
+    case STATE_IDLE:
+      switch (event) {
+        case EVENT_START_RECOGNITION:
+          return ConnectBothStreams(event_args);
+        case EVENT_END_RECOGNITION:
+        // Note AUDIO_CHUNK and AUDIO_END events can remain enqueued in case of
+        // abort, so we just silently drop them here.
+        case EVENT_AUDIO_CHUNK:
+        case EVENT_AUDIO_CHUNKS_ENDED:
+        // DOWNSTREAM_CLOSED can be received if we end up here due to an error.
+        case EVENT_DOWNSTREAM_CLOSED:
+          return DoNothing(event_args);
+        case EVENT_UPSTREAM_ERROR:
+        case EVENT_DOWNSTREAM_ERROR:
+        case EVENT_DOWNSTREAM_RESPONSE:
+          return NotFeasible(event_args);
+      }
+      break;
+    case STATE_BOTH_STREAMS_CONNECTED:
+      switch (event) {
+        case EVENT_AUDIO_CHUNK:
+          return TransmitAudioUpstream(event_args);
+        case EVENT_DOWNSTREAM_RESPONSE:
+          return ProcessDownstreamResponse(event_args);
+        case EVENT_AUDIO_CHUNKS_ENDED:
+          return CloseUpstreamAndWaitForResults(event_args);
+        case EVENT_END_RECOGNITION:
+          return AbortSilently(event_args);
+        case EVENT_UPSTREAM_ERROR:
+        case EVENT_DOWNSTREAM_ERROR:
+        case EVENT_DOWNSTREAM_CLOSED:
+          return AbortWithError(event_args);
+        case EVENT_START_RECOGNITION:
+          return NotFeasible(event_args);
+      }
+      break;
+    case STATE_WAITING_DOWNSTREAM_RESULTS:
+      switch (event) {
+        case EVENT_DOWNSTREAM_RESPONSE:
+          return ProcessDownstreamResponse(event_args);
+        case EVENT_DOWNSTREAM_CLOSED:
+          return RaiseNoMatchErrorIfGotNoResults(event_args);
+        case EVENT_END_RECOGNITION:
+          return AbortSilently(event_args);
+        case EVENT_UPSTREAM_ERROR:
+        case EVENT_DOWNSTREAM_ERROR:
+          return AbortWithError(event_args);
+        case EVENT_START_RECOGNITION:
+        case EVENT_AUDIO_CHUNK:
+        case EVENT_AUDIO_CHUNKS_ENDED:
+          return NotFeasible(event_args);
+      }
+      break;
+  }
+  return NotFeasible(event_args);
+}
+
+// ----------- Contract for all the FSM evolution functions below -------------
+//  - Are guaranteed to be executed in the same thread (IO, except for tests);
+//  - Are guaranteed to be not reentrant (themselves and each other);
+//  - event_args members are guaranteed to be stable during the call;
+
+SpeechRecognitionEngine::FSMState
+SpeechRecognitionEngine::ConnectBothStreams(const FSMEventArgs&) {
+  DCHECK(!upstream_fetcher_.get());
+  DCHECK(!downstream_fetcher_.get());
+
+  encoder_.reset(new AudioEncoder(config_.audio_sample_rate,
+                                  config_.audio_num_bits_per_sample));
+  DCHECK(encoder_.get());
+  const std::string request_key = GenerateRequestKey();
+
+  // Only use the framed post data format when a preamble needs to be logged.
+  use_framed_post_data_ = (config_.preamble &&
+                           !config_.preamble->sample_data.empty() &&
+                           !config_.auth_token.empty() &&
+                           !config_.auth_scope.empty());
+  if (use_framed_post_data_) {
+    preamble_encoder_.reset(new AudioEncoder(
+        config_.preamble->sample_rate,
+        config_.preamble->sample_depth * 8));
+  }
+
+  // Setup downstream fetcher.
+  std::vector<std::string> downstream_args;
+  downstream_args.push_back(
+      "key=" + net::EscapeQueryParamValue(google_apis::GetAPIKey(), true));
+  downstream_args.push_back("pair=" + request_key);
+  downstream_args.push_back("output=pb");
+  GURL downstream_url(std::string(kWebServiceBaseUrl) +
+                      std::string(kDownstreamUrl) +
+                      base::JoinString(downstream_args, "&"));
+
+  downstream_fetcher_ = URLFetcher::Create(
+      kDownstreamUrlFetcherIdForTesting, downstream_url, URLFetcher::GET, this);
+  downstream_fetcher_->SetRequestContext(url_context_.get());
+  downstream_fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SAVE_COOKIES |
+                                    net::LOAD_DO_NOT_SEND_COOKIES |
+                                    net::LOAD_DO_NOT_SEND_AUTH_DATA);
+  downstream_fetcher_->Start();
+
+  // Setup upstream fetcher.
+  // TODO(hans): Support for user-selected grammars.
+  std::vector<std::string> upstream_args;
+  upstream_args.push_back("key=" +
+      net::EscapeQueryParamValue(google_apis::GetAPIKey(), true));
+  upstream_args.push_back("pair=" + request_key);
+  upstream_args.push_back("output=pb");
+  upstream_args.push_back(
+      "lang=" + net::EscapeQueryParamValue(GetAcceptedLanguages(), true));
+  upstream_args.push_back(
+      config_.filter_profanities ? "pFilter=2" : "pFilter=0");
+  if (config_.max_hypotheses > 0U) {
+    uint32_t max_alternatives =
+        std::min(kMaxMaxAlternatives, config_.max_hypotheses);
+    upstream_args.push_back("maxAlternatives=" +
+                            base::UintToString(max_alternatives));
+  }
+  upstream_args.push_back("app=chromium");
+  if (!config_.hardware_info.empty()) {
+    upstream_args.push_back(
+        "xhw=" + net::EscapeQueryParamValue(config_.hardware_info, true));
+  }
+  for (const SpeechRecognitionGrammar& grammar : config_.grammars) {
+    std::string grammar_value(
+        base::DoubleToString(grammar.weight) + ":" + grammar.url);
+    upstream_args.push_back(
+        "grammar=" + net::EscapeQueryParamValue(grammar_value, true));
+  }
+  if (config_.continuous)
+    upstream_args.push_back("continuous");
+  else
+    upstream_args.push_back("endpoint=1");
+  if (config_.interim_results)
+    upstream_args.push_back("interim");
+  if (!config_.auth_token.empty() && !config_.auth_scope.empty()) {
+    upstream_args.push_back(
+        "authScope=" + net::EscapeQueryParamValue(config_.auth_scope, true));
+    upstream_args.push_back(
+        "authToken=" + net::EscapeQueryParamValue(config_.auth_token, true));
+  }
+  if (use_framed_post_data_) {
+    std::string audio_format;
+    if (preamble_encoder_)
+      audio_format = preamble_encoder_->GetMimeType() + ",";
+    audio_format += encoder_->GetMimeType();
+    upstream_args.push_back(
+        "audioFormat=" + net::EscapeQueryParamValue(audio_format, true));
+  }
+  GURL upstream_url(std::string(kWebServiceBaseUrl) +
+                    std::string(kUpstreamUrl) +
+                    base::JoinString(upstream_args, "&"));
+
+  upstream_fetcher_ = URLFetcher::Create(kUpstreamUrlFetcherIdForTesting,
+                                         upstream_url, URLFetcher::POST, this);
+  if (use_framed_post_data_)
+    upstream_fetcher_->SetChunkedUpload("application/octet-stream");
+  else
+    upstream_fetcher_->SetChunkedUpload(encoder_->GetMimeType());
+  upstream_fetcher_->SetRequestContext(url_context_.get());
+  upstream_fetcher_->SetReferrer(config_.origin_url);
+  upstream_fetcher_->SetLoadFlags(net::LOAD_DO_NOT_SAVE_COOKIES |
+                                  net::LOAD_DO_NOT_SEND_COOKIES |
+                                  net::LOAD_DO_NOT_SEND_AUTH_DATA);
+  upstream_fetcher_->Start();
+  previous_response_length_ = 0;
+
+  if (preamble_encoder_) {
+    // Encode and send preamble right away.
+    scoped_refptr<AudioChunk> chunk = new AudioChunk(
+        reinterpret_cast<const uint8_t*>(config_.preamble->sample_data.data()),
+        config_.preamble->sample_data.size(), config_.preamble->sample_depth);
+    preamble_encoder_->Encode(*chunk);
+    preamble_encoder_->Flush();
+    scoped_refptr<AudioChunk> encoded_data(
+        preamble_encoder_->GetEncodedDataAndClear());
+    UploadAudioChunk(encoded_data->AsString(), FRAME_PREAMBLE_AUDIO, false);
+  }
+  return STATE_BOTH_STREAMS_CONNECTED;
+}
+
+SpeechRecognitionEngine::FSMState
+SpeechRecognitionEngine::TransmitAudioUpstream(
+    const FSMEventArgs& event_args) {
+  DCHECK(upstream_fetcher_.get());
+  DCHECK(event_args.audio_data.get());
+  const AudioChunk& audio = *(event_args.audio_data.get());
+
+  DCHECK_EQ(audio.bytes_per_sample(), config_.audio_num_bits_per_sample / 8);
+  encoder_->Encode(audio);
+  scoped_refptr<AudioChunk> encoded_data(encoder_->GetEncodedDataAndClear());
+  UploadAudioChunk(encoded_data->AsString(), FRAME_RECOGNITION_AUDIO, false);
+  return state_;
+}
+
+SpeechRecognitionEngine::FSMState
+SpeechRecognitionEngine::ProcessDownstreamResponse(
+    const FSMEventArgs& event_args) {
+  DCHECK(event_args.response.get());
+
+  proto::SpeechRecognitionEvent ws_event;
+  if (!ws_event.ParseFromString(std::string(event_args.response->begin(),
+                                            event_args.response->end())))
+    return AbortWithError(event_args);
+
+  if (ws_event.has_status()) {
+    switch (ws_event.status()) {
+      case proto::SpeechRecognitionEvent::STATUS_SUCCESS:
+        break;
+      case proto::SpeechRecognitionEvent::STATUS_NO_SPEECH:
+        return Abort(SPEECH_RECOGNITION_ERROR_NO_SPEECH);
+      case proto::SpeechRecognitionEvent::STATUS_ABORTED:
+        return Abort(SPEECH_RECOGNITION_ERROR_ABORTED);
+      case proto::SpeechRecognitionEvent::STATUS_AUDIO_CAPTURE:
+        return Abort(SPEECH_RECOGNITION_ERROR_AUDIO_CAPTURE);
+      case proto::SpeechRecognitionEvent::STATUS_NETWORK:
+        return Abort(SPEECH_RECOGNITION_ERROR_NETWORK);
+      case proto::SpeechRecognitionEvent::STATUS_NOT_ALLOWED:
+        return Abort(SPEECH_RECOGNITION_ERROR_NOT_ALLOWED);
+      case proto::SpeechRecognitionEvent::STATUS_SERVICE_NOT_ALLOWED:
+        return Abort(SPEECH_RECOGNITION_ERROR_SERVICE_NOT_ALLOWED);
+      case proto::SpeechRecognitionEvent::STATUS_BAD_GRAMMAR:
+        return Abort(SPEECH_RECOGNITION_ERROR_BAD_GRAMMAR);
+      case proto::SpeechRecognitionEvent::STATUS_LANGUAGE_NOT_SUPPORTED:
+        return Abort(SPEECH_RECOGNITION_ERROR_LANGUAGE_NOT_SUPPORTED);
+    }
+  }
+
+  if (!config_.continuous && ws_event.has_endpoint() &&
+      ws_event.endpoint() == proto::SpeechRecognitionEvent::END_OF_UTTERANCE) {
+    delegate_->OnSpeechRecognitionEngineEndOfUtterance();
+  }
+
+  SpeechRecognitionResults results;
+  for (int i = 0; i < ws_event.result_size(); ++i) {
+    const proto::SpeechRecognitionResult& ws_result = ws_event.result(i);
+    results.push_back(SpeechRecognitionResult());
+    SpeechRecognitionResult& result = results.back();
+    result.is_provisional = !(ws_result.has_final() && ws_result.final());
+
+    if (!result.is_provisional)
+      got_last_definitive_result_ = true;
+
+    for (int j = 0; j < ws_result.alternative_size(); ++j) {
+      const proto::SpeechRecognitionAlternative& ws_alternative =
+          ws_result.alternative(j);
+      SpeechRecognitionHypothesis hypothesis;
+      if (ws_alternative.has_confidence())
+        hypothesis.confidence = ws_alternative.confidence();
+      else if (ws_result.has_stability())
+        hypothesis.confidence = ws_result.stability();
+      DCHECK(ws_alternative.has_transcript());
+      // TODO(hans): Perhaps the transcript should be required in the proto?
+      if (ws_alternative.has_transcript())
+        hypothesis.utterance = base::UTF8ToUTF16(ws_alternative.transcript());
+
+      result.hypotheses.push_back(hypothesis);
+    }
+  }
+  if (results.size()) {
+    delegate_->OnSpeechRecognitionEngineResults(results);
+  }
+
+  return state_;
+}
+
+SpeechRecognitionEngine::FSMState
+SpeechRecognitionEngine::RaiseNoMatchErrorIfGotNoResults(
+    const FSMEventArgs& event_args) {
+  if (!got_last_definitive_result_) {
+    // Provide an empty result to notify that recognition is ended with no
+    // errors, yet neither any further results.
+    delegate_->OnSpeechRecognitionEngineResults(SpeechRecognitionResults());
+  }
+  return AbortSilently(event_args);
+}
+
+SpeechRecognitionEngine::FSMState
+SpeechRecognitionEngine::CloseUpstreamAndWaitForResults(
+    const FSMEventArgs&) {
+  DCHECK(upstream_fetcher_.get());
+  DCHECK(encoder_.get());
+
+  DVLOG(1) <<  "Closing upstream.";
+
+  // The encoder requires a non-empty final buffer. So we encode a packet
+  // of silence in case encoder had no data already.
+  size_t sample_count =
+      config_.audio_sample_rate * kAudioPacketIntervalMs / 1000;
+  scoped_refptr<AudioChunk> dummy_chunk = new AudioChunk(
+      sample_count * sizeof(int16_t), encoder_->GetBitsPerSample() / 8);
+  encoder_->Encode(*dummy_chunk.get());
+  encoder_->Flush();
+  scoped_refptr<AudioChunk> encoded_dummy_data =
+      encoder_->GetEncodedDataAndClear();
+  DCHECK(!encoded_dummy_data->IsEmpty());
+  encoder_.reset();
+
+  UploadAudioChunk(encoded_dummy_data->AsString(),
+                   FRAME_RECOGNITION_AUDIO,
+                   true);
+  got_last_definitive_result_ = false;
+  return STATE_WAITING_DOWNSTREAM_RESULTS;
+}
+
+SpeechRecognitionEngine::FSMState
+SpeechRecognitionEngine::CloseDownstream(const FSMEventArgs&) {
+  DCHECK(!upstream_fetcher_.get());
+  DCHECK(downstream_fetcher_.get());
+
+  DVLOG(1) <<  "Closing downstream.";
+  downstream_fetcher_.reset();
+  return STATE_IDLE;
+}
+
+SpeechRecognitionEngine::FSMState
+SpeechRecognitionEngine::AbortSilently(const FSMEventArgs&) {
+  return Abort(SPEECH_RECOGNITION_ERROR_NONE);
+}
+
+SpeechRecognitionEngine::FSMState
+SpeechRecognitionEngine::AbortWithError(const FSMEventArgs&) {
+  return Abort(SPEECH_RECOGNITION_ERROR_NETWORK);
+}
+
+SpeechRecognitionEngine::FSMState SpeechRecognitionEngine::Abort(
+    SpeechRecognitionErrorCode error_code) {
+  DVLOG(1) << "Aborting with error " << error_code;
+
+  if (error_code != SPEECH_RECOGNITION_ERROR_NONE) {
+    delegate_->OnSpeechRecognitionEngineError(
+        SpeechRecognitionError(error_code));
+  }
+  downstream_fetcher_.reset();
+  upstream_fetcher_.reset();
+  encoder_.reset();
+  return STATE_IDLE;
+}
+
+SpeechRecognitionEngine::FSMState
+SpeechRecognitionEngine::DoNothing(const FSMEventArgs&) {
+  return state_;
+}
+
+SpeechRecognitionEngine::FSMState
+SpeechRecognitionEngine::NotFeasible(const FSMEventArgs& event_args) {
+  NOTREACHED() << "Unfeasible event " << event_args.event
+               << " in state " << state_;
+  return state_;
+}
+
+std::string SpeechRecognitionEngine::GetAcceptedLanguages() const {
+  std::string langs = config_.language;
+  if (langs.empty() && url_context_.get()) {
+    // If no language is provided then we use the first from the accepted
+    // language list. If this list is empty then it defaults to "en-US".
+    // Example of the contents of this list: "es,en-GB;q=0.8", ""
+    net::URLRequestContext* request_context =
+        url_context_->GetURLRequestContext();
+    DCHECK(request_context);
+    // TODO(pauljensen): SpeechRecognitionEngine should be constructed with
+    // a reference to the HttpUserAgentSettings rather than accessing the
+    // accept language through the URLRequestContext.
+    if (request_context->http_user_agent_settings()) {
+      std::string accepted_language_list =
+          request_context->http_user_agent_settings()->GetAcceptLanguage();
+      size_t separator = accepted_language_list.find_first_of(",;");
+      if (separator != std::string::npos)
+        langs = accepted_language_list.substr(0, separator);
+    }
+  }
+  if (langs.empty())
+    langs = "en-US";
+  return langs;
+}
+
+// TODO(primiano): Is there any utility in the codebase that already does this?
+std::string SpeechRecognitionEngine::GenerateRequestKey() const {
+  const int64_t kKeepLowBytes = 0x00000000FFFFFFFFLL;
+  const int64_t kKeepHighBytes = 0xFFFFFFFF00000000LL;
+
+  // Just keep the least significant bits of timestamp, in order to reduce
+  // probability of collisions.
+  int64_t key = (base::Time::Now().ToInternalValue() & kKeepLowBytes) |
+                (base::RandUint64() & kKeepHighBytes);
+  return base::HexEncode(reinterpret_cast<void*>(&key), sizeof(key));
+}
+
+void SpeechRecognitionEngine::UploadAudioChunk(const std::string& data,
+                                                   FrameType type,
+                                                   bool is_final) {
+  if (use_framed_post_data_) {
+    std::string frame(data.size() + 8, 0);
+    base::WriteBigEndian(&frame[0], static_cast<uint32_t>(data.size()));
+    base::WriteBigEndian(&frame[4], static_cast<uint32_t>(type));
+    frame.replace(8, data.size(), data);
+    upstream_fetcher_->AppendChunkToUpload(frame, is_final);
+  } else {
+    upstream_fetcher_->AppendChunkToUpload(data, is_final);
+  }
+}
+
+SpeechRecognitionEngine::FSMEventArgs::FSMEventArgs(FSMEvent event_value)
+    : event(event_value) {
 }
 
-SpeechRecognitionEngine::Config::~Config() {
+SpeechRecognitionEngine::FSMEventArgs::~FSMEventArgs() {
 }
 
 }  // namespace content