Miscellaneous changes split from https://codereview.webrtc.org/1230503003 .

These are mostly trivial changes and are separated out just to reduce the
diff on that change to the minimum possible.

Note explanatory comments on patch set 1.

BUG=none
TEST=none

Review URL: https://codereview.webrtc.org/1235643003

Cr-Commit-Position: refs/heads/master@{#9617}
diff --git a/webrtc/modules/audio_coding/main/test/PCMFile.cc b/webrtc/modules/audio_coding/main/test/PCMFile.cc
index 4f46098..4b08f75 100644
--- a/webrtc/modules/audio_coding/main/test/PCMFile.cc
+++ b/webrtc/modules/audio_coding/main/test/PCMFile.cc
@@ -150,8 +150,7 @@
       }
     } else {
       int16_t* stereo_audio = new int16_t[2 * audio_frame.samples_per_channel_];
-      int k;
-      for (k = 0; k < audio_frame.samples_per_channel_; k++) {
+      for (int k = 0; k < audio_frame.samples_per_channel_; k++) {
         stereo_audio[k << 1] = audio_frame.data_[k];
         stereo_audio[(k << 1) + 1] = audio_frame.data_[k];
       }