Add basic support for "googDucking" to getUserMedia on Windows.

media/audio/win/audio_low_latency_input_win.h

Index: media/audio/win/audio_low_latency_input_win.h
diff --git a/media/audio/win/audio_low_latency_input_win.h b/media/audio/win/audio_low_latency_input_win.h
index 99e1604925a6c05a17f855fc0fa10c7d51971e29..f8309156e16adfa9c8073323b89ae01b6a400e7c 100644
--- a/media/audio/win/audio_low_latency_input_win.h
+++ b/media/audio/win/audio_low_latency_input_win.h
@@ -88,6 +88,7 @@ class MEDIA_EXPORT WASAPIAudioInputStream
   WASAPIAudioInputStream(AudioManagerWin* manager,
                          const AudioParameters& params,
                          const std::string& device_id);
+
   // The dtor is typically called by the AudioManager only and it is usually
   // triggered by calling AudioInputStream::Close().
   virtual ~WASAPIAudioInputStream();
@@ -101,16 +102,11 @@ class MEDIA_EXPORT WASAPIAudioInputStream
   virtual void SetVolume(double volume) OVERRIDE;
   virtual double GetVolume() OVERRIDE;
 
-  // Retrieves the sample rate used by the audio engine for its internal
-  // processing/mixing of shared-mode streams given a specifed device.
-  static int HardwareSampleRate(const std::string& device_id);
-
-  // Retrieves the number of audio channels used by the audio engine for its
-  // internal processing/mixing of shared-mode streams given a specified device.
-  static uint32 HardwareChannelCount(const std::string& device_id);
-
   bool started() const { return started_; }
 
+  // Returns the default hardware audio parameters of the specific device.
+  static AudioParameters GetInputStreamParameters(const std::string& device_id);
+
  private:
   // DelegateSimpleThread::Delegate implementation.
   virtual void Run() OVERRIDE;
@@ -157,6 +153,9 @@ class MEDIA_EXPORT WASAPIAudioInputStream
   // Length of the audio endpoint buffer.
   uint32 endpoint_buffer_size_frames_;
 
+  // A copy of the supplied AudioParameter's |effects|.
+  const int effects_;
+
   // Contains the unique name of the selected endpoint device.
   // Note that AudioManagerBase::kDefaultDeviceId represents the default
   // device role and is not a valid ID as such.
@@ -178,7 +177,7 @@ class MEDIA_EXPORT WASAPIAudioInputStream
   // An IMMDevice interface which represents an audio endpoint device.
   base::win::ScopedComPtr<IMMDevice> endpoint_device_;
 
-  // Windows Audio Session API (WASAP) interfaces.
+  // Windows Audio Session API (WASAPI) interfaces.
 
   // An IAudioClient interface which enables a client to create and initialize
   // an audio stream between an audio application and the audio engine.