[NOT FOR REVIEW] Convert channel counts to size_t.

webrtc/modules/audio_processing/high_pass_filter_impl.cc

Index: webrtc/modules/audio_processing/high_pass_filter_impl.cc
diff --git a/webrtc/modules/audio_processing/high_pass_filter_impl.cc b/webrtc/modules/audio_processing/high_pass_filter_impl.cc
index 6302f13fcf985081c2c3fdf8e63addc5dba4225e..ee27589ef5006166bef1062b6e9cf88c5d54acd0 100644
--- a/webrtc/modules/audio_processing/high_pass_filter_impl.cc
+++ b/webrtc/modules/audio_processing/high_pass_filter_impl.cc
@@ -116,7 +116,7 @@ int HighPassFilterImpl::ProcessCaptureAudio(AudioBuffer* audio) {
 
   assert(audio->num_frames_per_band() <= 160);
 
-  for (int i = 0; i < num_handles(); i++) {
+  for (size_t i = 0; i < num_handles(); i++) {
     Handle* my_handle = static_cast<Handle*>(handle(i));
     err = Filter(my_handle,
                  audio->split_bands(i)[kBand0To8kHz],
@@ -156,7 +156,7 @@ int HighPassFilterImpl::ConfigureHandle(void* /*handle*/) const {
   return apm_->kNoError; // Not configurable.
 }
 
-int HighPassFilterImpl::num_handles_required() const {
+size_t HighPassFilterImpl::num_handles_required() const {
   return apm_->num_output_channels();
 }