Add channel_count parameter back to AudioBuffer creation methods.

media/base/audio_buffer.cc

Index: media/base/audio_buffer.cc
diff --git a/media/base/audio_buffer.cc b/media/base/audio_buffer.cc
index eba658bf02691b1e4377903a769454cf93af24e7..4b972b90a1abda47c363b0cd46c7c8362ca60ee2 100644
--- a/media/base/audio_buffer.cc
+++ b/media/base/audio_buffer.cc
@@ -13,6 +13,7 @@ namespace media {
 
 AudioBuffer::AudioBuffer(SampleFormat sample_format,
                          ChannelLayout channel_layout,
+                         int channel_count,
                          int sample_rate,
                          int frame_count,
                          bool create_buffer,
@@ -21,7 +22,7 @@ AudioBuffer::AudioBuffer(SampleFormat sample_format,
                          const base::TimeDelta duration)
     : sample_format_(sample_format),
       channel_layout_(channel_layout),
-      channel_count_(ChannelLayoutToChannelCount(channel_layout)),
+      channel_count_(channel_count),
       sample_rate_(sample_rate),
       adjusted_frame_count_(frame_count),
       trim_start_(0),
@@ -31,6 +32,9 @@ AudioBuffer::AudioBuffer(SampleFormat sample_format,
   CHECK_GE(channel_count_, 0);
   CHECK_LE(channel_count_, limits::kMaxChannels);
   CHECK_GE(frame_count, 0);
+  DCHECK(channel_layout == CHANNEL_LAYOUT_DISCRETE ||
+         ChannelLayoutToChannelCount(channel_layout) == channel_count);
+
   int bytes_per_channel = SampleFormatToBytesPerChannel(sample_format);
   DCHECK_LE(bytes_per_channel, kChannelAlignment);
   int data_size = frame_count * bytes_per_channel;
@@ -83,6 +87,7 @@ AudioBuffer::~AudioBuffer() {}
 scoped_refptr<AudioBuffer> AudioBuffer::CopyFrom(
     SampleFormat sample_format,
     ChannelLayout channel_layout,
+    int channel_count,
     int sample_rate,
     int frame_count,
     const uint8* const* data,
@@ -93,6 +98,7 @@ scoped_refptr<AudioBuffer> AudioBuffer::CopyFrom(
   CHECK(data[0]);
   return make_scoped_refptr(new AudioBuffer(sample_format,
                                             channel_layout,
+                                            channel_count,
                                             sample_rate,
                                             frame_count,
                                             true,
@@ -105,11 +111,13 @@ scoped_refptr<AudioBuffer> AudioBuffer::CopyFrom(
 scoped_refptr<AudioBuffer> AudioBuffer::CreateBuffer(
     SampleFormat sample_format,
     ChannelLayout channel_layout,
+    int channel_count,
     int sample_rate,
     int frame_count) {
   CHECK_GT(frame_count, 0);  // Otherwise looks like an EOF buffer.
   return make_scoped_refptr(new AudioBuffer(sample_format,
                                             channel_layout,
+                                            channel_count,
                                             sample_rate,
                                             frame_count,
                                             true,
@@ -121,6 +129,7 @@ scoped_refptr<AudioBuffer> AudioBuffer::CreateBuffer(
 // static
 scoped_refptr<AudioBuffer> AudioBuffer::CreateEmptyBuffer(
     ChannelLayout channel_layout,
+    int channel_count,
     int sample_rate,
     int frame_count,
     const base::TimeDelta timestamp,
@@ -129,6 +138,7 @@ scoped_refptr<AudioBuffer> AudioBuffer::CreateEmptyBuffer(
   // Since data == NULL, format doesn't matter.
   return make_scoped_refptr(new AudioBuffer(kSampleFormatF32,
                                             channel_layout,
+                                            channel_count,
                                             sample_rate,
                                             frame_count,
                                             false,
@@ -143,6 +153,7 @@ scoped_refptr<AudioBuffer> AudioBuffer::CreateEOSBuffer() {
                                             CHANNEL_LAYOUT_NONE,
                                             0,
                                             0,
+                                            0,
                                             false,
                                             NULL,
                                             kNoTimestamp(),