Update a ton of audio code to use size_t more correctly and in general reduce
use of int16_t/uint16_t.

This is the upshot of a recommendation by henrik.lundin and kwiberg on an original small change ( https://webrtc-codereview.appspot.com/42569004/#ps1 ) to stop using int16_t just because values could fit in it, and is similar in nature to a previous "mass change to use size_t more" ( https://webrtc-codereview.appspot.com/23129004/ ) which also needed to be split up for review but to land all at once, since, like adding "const", such changes tend to cause a lot of transitive effects.

This was be reviewed and approved in pieces:
https://codereview.webrtc.org/1224093003
https://codereview.webrtc.org/1224123002
https://codereview.webrtc.org/1224163002
https://codereview.webrtc.org/1225133003
https://codereview.webrtc.org/1225173002
https://codereview.webrtc.org/1227163003
https://codereview.webrtc.org/1227203003
https://codereview.webrtc.org/1227213002
https://codereview.webrtc.org/1227893002
https://codereview.webrtc.org/1228793004
https://codereview.webrtc.org/1228803003
https://codereview.webrtc.org/1228823002
https://codereview.webrtc.org/1228823003
https://codereview.webrtc.org/1228843002
https://codereview.webrtc.org/1230693002
https://codereview.webrtc.org/1231713002

The change is being landed as TBR to all the folks who reviewed the above.

BUG=chromium:81439
TEST=none
R=andrew@webrtc.org, pbos@webrtc.org
TBR=aluebs, andrew, asapersson, henrika, hlundin, jan.skoglund, kwiberg, minyue, pbos, pthatcher

Review URL: https://codereview.webrtc.org/1230503003 .

Cr-Commit-Position: refs/heads/master@{#9768}
diff --git a/webrtc/modules/audio_coding/main/acm2/acm_receiver.cc b/webrtc/modules/audio_coding/main/acm2/acm_receiver.cc
index 4c11197..1cefeb6 100644
--- a/webrtc/modules/audio_coding/main/acm2/acm_receiver.cc
+++ b/webrtc/modules/audio_coding/main/acm2/acm_receiver.cc
@@ -344,7 +344,7 @@
 
 int AcmReceiver::GetAudio(int desired_freq_hz, AudioFrame* audio_frame) {
   enum NetEqOutputType type;
-  int samples_per_channel;
+  size_t samples_per_channel;
   int num_channels;
   bool return_silence = false;
 
@@ -394,7 +394,7 @@
   }
 
   // NetEq always returns 10 ms of audio.
-  current_sample_rate_hz_ = samples_per_channel * 100;
+  current_sample_rate_hz_ = static_cast<int>(samples_per_channel * 100);
 
   // Update if resampling is required.
   bool need_resampling = (desired_freq_hz != -1) &&
@@ -403,18 +403,19 @@
   if (need_resampling && !resampled_last_output_frame_) {
     // Prime the resampler with the last frame.
     int16_t temp_output[AudioFrame::kMaxDataSizeSamples];
-    samples_per_channel =
+    int samples_per_channel_int =
         resampler_.Resample10Msec(last_audio_buffer_.get(),
                                   current_sample_rate_hz_,
                                   desired_freq_hz,
                                   num_channels,
                                   AudioFrame::kMaxDataSizeSamples,
                                   temp_output);
-    if (samples_per_channel < 0) {
+    if (samples_per_channel_int < 0) {
       LOG(LERROR) << "AcmReceiver::GetAudio - "
                      "Resampling last_audio_buffer_ failed.";
       return -1;
     }
+    samples_per_channel = static_cast<size_t>(samples_per_channel_int);
   }
 
   // The audio in |audio_buffer_| is tansferred to |audio_frame_| below, either
@@ -422,17 +423,18 @@
   // TODO(henrik.lundin) Glitches in the output may appear if the output rate
   // from NetEq changes. See WebRTC issue 3923.
   if (need_resampling) {
-    samples_per_channel =
+    int samples_per_channel_int =
         resampler_.Resample10Msec(audio_buffer_.get(),
                                   current_sample_rate_hz_,
                                   desired_freq_hz,
                                   num_channels,
                                   AudioFrame::kMaxDataSizeSamples,
                                   audio_frame->data_);
-    if (samples_per_channel < 0) {
+    if (samples_per_channel_int < 0) {
       LOG(LERROR) << "AcmReceiver::GetAudio - Resampling audio_buffer_ failed.";
       return -1;
     }
+    samples_per_channel = static_cast<size_t>(samples_per_channel_int);
     resampled_last_output_frame_ = true;
   } else {
     resampled_last_output_frame_ = false;
@@ -448,7 +450,7 @@
 
   audio_frame->num_channels_ = num_channels;
   audio_frame->samples_per_channel_ = samples_per_channel;
-  audio_frame->sample_rate_hz_ = samples_per_channel * 100;
+  audio_frame->sample_rate_hz_ = static_cast<int>(samples_per_channel * 100);
 
   // Should set |vad_activity| before calling SetAudioFrameActivityAndType().
   audio_frame->vad_activity_ = previous_audio_activity_;
@@ -787,10 +789,11 @@
     frame->sample_rate_hz_ = current_sample_rate_hz_;
   }
 
-  frame->samples_per_channel_ = frame->sample_rate_hz_ / 100;  // Always 10 ms.
+  frame->samples_per_channel_ =
+      static_cast<size_t>(frame->sample_rate_hz_ / 100);  // Always 10 ms.
   frame->speech_type_ = AudioFrame::kCNG;
   frame->vad_activity_ = AudioFrame::kVadPassive;
-  int samples = frame->samples_per_channel_ * frame->num_channels_;
+  size_t samples = frame->samples_per_channel_ * frame->num_channels_;
   memset(frame->data_, 0, samples * sizeof(int16_t));
   return true;
 }