Update audio code to use size_t more correctly, webrtc/modules/audio_processing/

webrtc/modules/audio_processing/beamformer/matrix.h

Index: webrtc/modules/audio_processing/beamformer/matrix.h
diff --git a/webrtc/modules/audio_processing/beamformer/matrix.h b/webrtc/modules/audio_processing/beamformer/matrix.h
index 990f6a4a1b7ac6d74d907a368db6793a5fce230b..1a961aff07edd9fc32cc6871634527b1e665b5ff 100644
--- a/webrtc/modules/audio_processing/beamformer/matrix.h
+++ b/webrtc/modules/audio_processing/beamformer/matrix.h
@@ -95,7 +95,9 @@ class Matrix {
     memcpy(&data_[0], data, num_rows_ * num_columns_ * sizeof(data_[0]));
   }
 
-  Matrix& CopyFromColumn(const T* const* src, int column_index, int num_rows) {
+  Matrix& CopyFromColumn(const T* const* src,
+                         size_t column_index,
+                         int num_rows) {
     Resize(1, num_rows);
     for (int i = 0; i < num_columns_; ++i) {
       data_[i] = src[i][column_index];