Remove the last piece of deprecated synchronous IO code.

media/audio/audio_parameters.h

Index: media/audio/audio_parameters.h
diff --git a/media/audio/audio_parameters.h b/media/audio/audio_parameters.h
index b23d26fdcae0e9ff57f310a826348cfea2a11a39..03fe043dfadd53e4ae4bf75edc1e9ce5eeadcacf 100644
--- a/media/audio/audio_parameters.h
+++ b/media/audio/audio_parameters.h
@@ -58,17 +58,14 @@ class MEDIA_EXPORT AudioParameters {
                   int sample_rate, int bits_per_sample,
                   int frames_per_buffer);
   AudioParameters(Format format, ChannelLayout channel_layout,
-                  int input_channels,
                   int sample_rate, int bits_per_sample,
                   int frames_per_buffer, int effects);
   AudioParameters(Format format, ChannelLayout channel_layout,

[xians, 2014/08/12 13:12:35]

Andrew, you added this constructor in https://codereview.chromium.org/115413002,
but I don't see any use case in our code, do you mind telling me why it is
desired? I would like to remove it if it is not needed?

[ajm, 2014/08/13 00:40:41]

I'm guessing the code that used it was since removed. If it's really not used,
feel free to remove it.

[no longer working on chromium, 2014/08/13 15:24:58]

Thanks Andrew, it turns out that the code is used by some unittest and
audio_manager_mac.cc, I have to keep it for now.

-                  int channels, int input_channels,
-                  int sample_rate, int bits_per_sample,
+                  int channels, int sample_rate, int bits_per_sample,
                   int frames_per_buffer, int effects);
 
   void Reset(Format format, ChannelLayout channel_layout,
-             int channels, int input_channels,
-             int sample_rate, int bits_per_sample,
+             int channels, int sample_rate, int bits_per_sample,
              int frames_per_buffer);
 
   // Checks that all values are in the expected range. All limits are specified
@@ -94,7 +91,6 @@ class MEDIA_EXPORT AudioParameters {
   int bits_per_sample() const { return bits_per_sample_; }
   int frames_per_buffer() const { return frames_per_buffer_; }
   int channels() const { return channels_; }
-  int input_channels() const { return input_channels_; }
   int effects() const { return effects_; }
 
   // Comparison with other AudioParams.
@@ -103,7 +99,6 @@ class MEDIA_EXPORT AudioParameters {
            sample_rate_ == other.sample_rate() &&
            channel_layout_ == other.channel_layout() &&
            channels_ == other.channels() &&
-           input_channels_ == other.input_channels() &&
            bits_per_sample_ == other.bits_per_sample() &&
            frames_per_buffer_ == other.frames_per_buffer() &&
            effects_ == other.effects();
@@ -120,9 +115,6 @@ class MEDIA_EXPORT AudioParameters {
 
   int channels_;                  // Number of channels. Value set based on
                                   // |channel_layout|.
-  int input_channels_;            // Optional number of input channels.
-                                  // Normally 0, but can be set to specify
-                                  // synchronized I/O.
   int effects_;                   // Bitmask using PlatformEffectsMask.
 };
 
@@ -132,8 +124,6 @@ inline bool operator<(const AudioParameters& a, const AudioParameters& b) {
     return a.format() < b.format();
   if (a.channels() != b.channels())
     return a.channels() < b.channels();
-  if (a.input_channels() != b.input_channels())
-    return a.input_channels() < b.input_channels();
   if (a.sample_rate() != b.sample_rate())
     return a.sample_rate() < b.sample_rate();
   if (a.bits_per_sample() != b.bits_per_sample())