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/system_wrappers/source/aligned_array_unittest.cc b/webrtc/system_wrappers/source/aligned_array_unittest.cc
index f25c717..8b8d50d 100644
--- a/webrtc/system_wrappers/source/aligned_array_unittest.cc
+++ b/webrtc/system_wrappers/source/aligned_array_unittest.cc
@@ -34,16 +34,16 @@
 }
 
 TEST(AlignedArrayTest, CheckOverlap) {
-  AlignedArray<int> arr(10, 7, 128);
+  AlignedArray<size_t> arr(10, 7, 128);
 
   for (int i = 0; i < 10; ++i) {
-    for (int j = 0; j < 7; ++j) {
+    for (size_t j = 0; j < 7; ++j) {
       arr.At(i, j) = 20 * i + j;
     }
   }
 
   for (int i = 0; i < 10; ++i) {
-    for (int j = 0; j < 7; ++j) {
+    for (size_t j = 0; j < 7; ++j) {
       ASSERT_EQ(arr.At(i, j), 20 * i + j);
       ASSERT_EQ(arr.Row(i)[j], 20 * i + j);
       ASSERT_EQ(arr.Array()[i][j], 20 * i + j);
@@ -54,7 +54,7 @@
 TEST(AlignedArrayTest, CheckRowsCols) {
   AlignedArray<bool> arr(10, 7, 128);
   ASSERT_EQ(arr.rows(), 10);
-  ASSERT_EQ(arr.cols(), 7);
+  ASSERT_EQ(arr.cols(), 7u);
 }
 
 }  // namespace webrtc