AudioBuffer: Eliminate the SplitChannelBuffer class

It's just a container for two IFChannelBuffers, and doesn't earn its
keep. The main problem is that the number of methods it needs that
just forward calls to either of its two IFChannelBuffers was already
large, and was about to grow.

R=aluebs@webrtc.org, minyue@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/16919004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6717 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/modules/audio_processing/audio_buffer.h b/webrtc/modules/audio_processing/audio_buffer.h
index 6b1a46f..5c26ae2 100644
--- a/webrtc/modules/audio_processing/audio_buffer.h
+++ b/webrtc/modules/audio_processing/audio_buffer.h
@@ -23,7 +23,6 @@
 namespace webrtc {
 
 class PushSincResampler;
-class SplitChannelBuffer;
 class IFChannelBuffer;
 
 struct SplitFilterStates {
@@ -115,7 +114,8 @@
 
   const float* keyboard_data_;
   scoped_ptr<IFChannelBuffer> channels_;
-  scoped_ptr<SplitChannelBuffer> split_channels_;
+  scoped_ptr<IFChannelBuffer> split_channels_low_;
+  scoped_ptr<IFChannelBuffer> split_channels_high_;
   scoped_ptr<SplitFilterStates[]> filter_states_;
   scoped_ptr<ChannelBuffer<int16_t> > mixed_low_pass_channels_;
   scoped_ptr<ChannelBuffer<int16_t> > low_pass_reference_channels_;