Prepare to convert various types to size_t.

webrtc/modules/audio_coding/codecs/opus/opus_unittest.cc

Index: webrtc/modules/audio_coding/codecs/opus/opus_unittest.cc
diff --git a/webrtc/modules/audio_coding/codecs/opus/opus_unittest.cc b/webrtc/modules/audio_coding/codecs/opus/opus_unittest.cc
index 9289933c04ad88fec98a15deac3afb97b15dc6de..2a88772a864464fcf103fbe4cc1c9e77b9c5b39e 100644
--- a/webrtc/modules/audio_coding/codecs/opus/opus_unittest.cc
+++ b/webrtc/modules/audio_coding/codecs/opus/opus_unittest.cc
@@ -105,6 +105,7 @@ int OpusTest::EncodeDecode(WebRtcOpusEncInst* encoder,
                                     input_audio,
                                     input_samples, kMaxBytes,
                                     bitstream_);
+  EXPECT_GE(encoded_bytes_, 0);
   return WebRtcOpus_Decode(decoder, bitstream_,
                            encoded_bytes_, output_audio,
                            audio_type);
@@ -538,6 +539,7 @@ TEST_P(OpusTest, OpusDurationEstimation) {
                                      speech_data_.GetNextBlock(),
                                      kOpus10msFrameSamples, kMaxBytes,
                                      bitstream_);
+  EXPECT_GE(encoded_bytes_, 0);
   EXPECT_EQ(kOpus10msFrameSamples,
             WebRtcOpus_DurationEst(opus_decoder_, bitstream_,
                                    encoded_bytes_));
@@ -547,6 +549,7 @@ TEST_P(OpusTest, OpusDurationEstimation) {
                                      speech_data_.GetNextBlock(),
                                      kOpus20msFrameSamples, kMaxBytes,
                                      bitstream_);
+  EXPECT_GE(encoded_bytes_, 0);
   EXPECT_EQ(kOpus20msFrameSamples,
             WebRtcOpus_DurationEst(opus_decoder_, bitstream_,
                                    encoded_bytes_));