Refactor AudioParameters member setting.

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 a73982e6ba259721770158a9c00bbf707b28f283..57fb960e488fe09a4532f9cbeb321ed61d9b6a92 100644
--- a/media/audio/audio_parameters.h
+++ b/media/audio/audio_parameters.h
@@ -80,18 +80,17 @@ class MEDIA_EXPORT AudioParameters {
   };
 
   AudioParameters();
-  AudioParameters(Format format, ChannelLayout channel_layout,
-                  int sample_rate, int bits_per_sample,
+  AudioParameters(Format format,
+                  ChannelLayout channel_layout,
+                  int sample_rate,

[tommi (sloooow) - chröme, 2015/09/05 09:49:58]

this is a great improvement over how things were.  It's still possible to make
mistakes since we have three ints in a row. Maybe we should strongly type these
in the future. E.g. have an enum, typedef or even a class for sample rate, bits
per sample etc.

[ajm, 2015/09/06 07:24:14]

I could see using an enum for bits_per_sample, since there aren't a lot of
possibilities.

+                  int bits_per_sample,
                   int frames_per_buffer);
-  AudioParameters(Format format, ChannelLayout channel_layout,
-                  int sample_rate, int bits_per_sample,
-                  int frames_per_buffer, int effects);
-  AudioParameters(Format format, ChannelLayout channel_layout,
-                  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 sample_rate, int bits_per_sample,
+
+  // Re-initializes all members.
+  void Reset(Format format,
+             ChannelLayout channel_layout,
+             int sample_rate,
+             int bits_per_sample,
              int frames_per_buffer);
 
   // Checks that all values are in the expected range. All limits are specified
@@ -118,25 +117,48 @@ class MEDIA_EXPORT AudioParameters {
   // Comparison with other AudioParams.
   bool Equals(const AudioParameters& other) const;
 
+  void set_format(Format format) { format_ = format; }
   Format format() const { return format_; }
+
+  // A setter for channel_layout_ is intentionally excluded.
   ChannelLayout channel_layout() const { return channel_layout_; }
+
+  // The number of channels is usually computed from channel_layout_. Setting
+  // this explictly is only required with CHANNEL_LAYOUT_DISCRETE.
+  void set_channels_for_discrete(int channels) {
+    DCHECK(channel_layout_ == CHANNEL_LAYOUT_DISCRETE ||
+           channels == ChannelLayoutToChannelCount(channel_layout_));
+    channels_ = channels;
+  }
+  int channels() const { return channels_; }
+
+  void set_sample_rate(int sample_rate) { sample_rate_ = sample_rate; }
   int sample_rate() const { return sample_rate_; }
+
+  void set_bits_per_sample(int bits_per_sample) {
+    bits_per_sample_ = bits_per_sample;
+  }
   int bits_per_sample() const { return bits_per_sample_; }
+
+  void set_frames_per_buffer(int frames_per_buffer) {
+    frames_per_buffer_ = frames_per_buffer;
+  }
   int frames_per_buffer() const { return frames_per_buffer_; }
-  int channels() const { return channels_; }
+
+  void set_effects(int effects) { effects_ = effects; }
   int effects() const { return effects_; }
 
+  AudioParameters(const AudioParameters&) = default;
+  AudioParameters& operator=(const AudioParameters&) = default;
+
  private:
-  // These members are mutable to support entire struct assignment. They should
-  // not be mutated individually.
   Format format_;                 // Format of the stream.
   ChannelLayout channel_layout_;  // Order of surround sound channels.
+  int channels_;                  // Number of channels. Value set based on
+                                  // |channel_layout|.
   int sample_rate_;               // Sampling frequency/rate.
   int bits_per_sample_;           // Number of bits per sample.
   int frames_per_buffer_;         // Number of frames in a buffer.
-
-  int channels_;                  // Number of channels. Value set based on
-                                  // |channel_layout|.
   int effects_;                   // Bitmask using PlatformEffectsMask.
 };