clang/win: Let remaining chromium_code targets build with -Wextra.

media/audio/win/audio_low_latency_output_win_unittest.cc

Index: media/audio/win/audio_low_latency_output_win_unittest.cc
diff --git a/media/audio/win/audio_low_latency_output_win_unittest.cc b/media/audio/win/audio_low_latency_output_win_unittest.cc
index 4c39228f7d9877fdb66e773031120e1ef2a13084..5c2d4572fab14c302ba6aac0389a87f23aeed08f 100644
--- a/media/audio/win/audio_low_latency_output_win_unittest.cc
+++ b/media/audio/win/audio_low_latency_output_win_unittest.cc
@@ -432,7 +432,7 @@ TEST(WASAPIAudioOutputStreamTest, DISABLED_ReadFromStereoFile) {
   DVLOG(0) << "#file segments : " << kNumFileSegments;
   DVLOG(0) << ">> Listen to the stereo file while playing...";
 
-  for (int i = 0; i < kNumFileSegments; i++) {
+  for (size_t i = 0; i < kNumFileSegments; i++) {
     // Each segment will start with a short (~20ms) block of zeros, hence
     // some short glitches might be heard in this test if kNumFileSegments
     // is larger than one. The exact length of the silence period depends on