Speech input: Do environment estimation and detect the no-speech case.

chrome/browser/speech/endpointer/energy_endpointer.h

 // Copyright (c) 2010 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.
 
 // The EnergyEndpointer class finds likely speech onset and offset points.
 //
 // The implementation described here is about the simplest possible.
 // It is based on timings of threshold crossings for overall signal
 // RMS. It is suitable for light weight applications.
 //
@@ skipping 66 matching lines @@
   void SetUserInputMode();
 
   // Computes the next input frame and modifies EnergyEndpointer status as
   // appropriate based on the computation.
   void ProcessAudioFrame(int64 time_us, const int16* samples, int num_samples);
 
   // Returns the current state of the EnergyEndpointer and the time
   // corresponding to the most recently computed frame.
   EpStatus Status(int64* status_time_us) const;
 
+  bool estimating_environment() const {
+    return estimating_environment_;
+  }
+
  private:
   class HistoryRing;
 
   // Resets the endpointer internal state.  If reset_threshold is true, the
   // state will be reset completely, including adaptive thresholds and the
   // removal of all history information.
   void Restart(bool reset_threshold);
 
   // Update internal speech and noise levels.
   void UpdateLevels(float rms);
@@ skipping 38 matching lines @@
   // Time when mode switched from environment estimation to user input. This
   // is used to time forced rejection of audio feedback contamination.
   int64 user_input_start_time_us_;
 
   DISALLOW_COPY_AND_ASSIGN(EnergyEndpointer);
 };
 
 }  // namespace speech_input
 
 #endif  // CHROME_BROWSER_SPEECH_ENDPOINTER_ENERGY_ENDPOINTER_H_