Update a ton of audio code to use size_t more correctly and in general reduce

webrtc/modules/audio_coding/neteq/mock/mock_external_decoder_pcm16b.h

Index: webrtc/modules/audio_coding/neteq/mock/mock_external_decoder_pcm16b.h
diff --git a/webrtc/modules/audio_coding/neteq/mock/mock_external_decoder_pcm16b.h b/webrtc/modules/audio_coding/neteq/mock/mock_external_decoder_pcm16b.h
index d8c88561a2eb1bffa84222b941c0904eaf6328f6..f239b4aa3a77f1e40e9f8865dc876c0deaf6c758 100644
--- a/webrtc/modules/audio_coding/neteq/mock/mock_external_decoder_pcm16b.h
+++ b/webrtc/modules/audio_coding/neteq/mock/mock_external_decoder_pcm16b.h
@@ -36,10 +36,9 @@ class ExternalPcm16B : public AudioDecoder {
                      int sample_rate_hz,
                      int16_t* decoded,
                      SpeechType* speech_type) override {
-    int16_t ret = WebRtcPcm16b_Decode(
-        encoded, static_cast<int16_t>(encoded_len), decoded);
+    size_t ret = WebRtcPcm16b_Decode(encoded, encoded_len, decoded);
     *speech_type = ConvertSpeechType(1);
-    return ret;
+    return static_cast<int>(ret);
   }
   size_t Channels() const override { return 1; }
 
@@ -79,7 +78,7 @@ class MockExternalPcm16B : public ExternalPcm16B {
   MOCK_CONST_METHOD0(HasDecodePlc,
       bool());
   MOCK_METHOD2(DecodePlc,
-      int(int num_frames, int16_t* decoded));
+      size_t(size_t num_frames, int16_t* decoded));
   MOCK_METHOD0(Init,
       int());
   MOCK_METHOD5(IncomingPacket,