[NOT FOR REVIEW] Convert channel counts to size_t.

webrtc/modules/audio_processing/echo_cancellation_impl.cc

Index: webrtc/modules/audio_processing/echo_cancellation_impl.cc
diff --git a/webrtc/modules/audio_processing/echo_cancellation_impl.cc b/webrtc/modules/audio_processing/echo_cancellation_impl.cc
index 86ed9234c78bb59cb98da33fbce664a0678ac5d0..fac477d9f7569f61a46ea1fc4452ed3a8641693e 100644
--- a/webrtc/modules/audio_processing/echo_cancellation_impl.cc
+++ b/webrtc/modules/audio_processing/echo_cancellation_impl.cc
@@ -85,8 +85,8 @@ int EchoCancellationImpl::ProcessRenderAudio(const AudioBuffer* audio) {
 
   // The ordering convention must be followed to pass to the correct AEC.
   size_t handle_index = 0;
-  for (int i = 0; i < apm_->num_output_channels(); i++) {
-    for (int j = 0; j < audio->num_channels(); j++) {
+  for (size_t i = 0; i < apm_->num_output_channels(); i++) {
+    for (size_t j = 0; j < audio->num_channels(); j++) {
       Handle* my_handle = static_cast<Handle*>(handle(handle_index));
       err = WebRtcAec_BufferFarend(
           my_handle,
@@ -125,8 +125,8 @@ int EchoCancellationImpl::ProcessCaptureAudio(AudioBuffer* audio) {
   // The ordering convention must be followed to pass to the correct AEC.
   size_t handle_index = 0;
   stream_has_echo_ = false;
-  for (int i = 0; i < audio->num_channels(); i++) {
-    for (int j = 0; j < apm_->num_reverse_channels(); j++) {
+  for (size_t i = 0; i < audio->num_channels(); i++) {
+    for (size_t j = 0; j < apm_->num_reverse_channels(); j++) {
       Handle* my_handle = handle(handle_index);
       err = WebRtcAec_Process(
           my_handle,
@@ -369,7 +369,7 @@ int EchoCancellationImpl::ConfigureHandle(void* handle) const {
   return WebRtcAec_set_config(static_cast<Handle*>(handle), config);
 }
 
-int EchoCancellationImpl::num_handles_required() const {
+size_t EchoCancellationImpl::num_handles_required() const {
   return apm_->num_output_channels() *
          apm_->num_reverse_channels();
 }