Revert of Allow more than 2 input channels in AudioProcessing.

webrtc/common_audio/wav_file.cc

Index: webrtc/common_audio/wav_file.cc
diff --git a/webrtc/common_audio/wav_file.cc b/webrtc/common_audio/wav_file.cc
index a0c792c54a6fab246dd66afca5af860cdb53a7f8..995043461a18a692745ce747dab7afa4c9a8d9cf 100644
--- a/webrtc/common_audio/wav_file.cc
+++ b/webrtc/common_audio/wav_file.cc
@@ -123,6 +123,11 @@
   num_samples_ += static_cast<uint32_t>(written);
   CHECK(written <= std::numeric_limits<uint32_t>::max() ||
         num_samples_ >= written);  // detect uint32_t overflow
+  CHECK(CheckWavParameters(num_channels_,
+                           sample_rate_,
+                           kWavFormat,
+                           kBytesPerSample,
+                           num_samples_));
 }
 
 void WavWriter::WriteSamples(const float* samples, size_t num_samples) {