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/modules/audio_coding/codecs/ilbc/decode.c b/webrtc/modules/audio_coding/codecs/ilbc/decode.c
index 9918de2..4c8497a 100644
--- a/webrtc/modules/audio_coding/codecs/ilbc/decode.c
+++ b/webrtc/modules/audio_coding/codecs/ilbc/decode.c
@@ -44,7 +44,7 @@
     int16_t mode      /* (i) 0: bad packet, PLC,
                                                                    1: normal */
                            ) {
-  int i;
+  size_t i;
   int16_t order_plus_one;
 
   int16_t last_bit;
@@ -106,7 +106,7 @@
       WebRtcIlbcfix_DoThePlc(
           PLCresidual, PLClpc, 0, decresidual,
           syntdenum + (LPC_FILTERORDER + 1) * (iLBCdec_inst->nsub - 1),
-          (int16_t)(iLBCdec_inst->last_lag), iLBCdec_inst);
+          iLBCdec_inst->last_lag, iLBCdec_inst);
 
       /* Use the output from doThePLC */
       WEBRTC_SPL_MEMCPY_W16(decresidual, PLCresidual, iLBCdec_inst->blockl);
@@ -122,7 +122,7 @@
     /* packet loss conceal */
 
     WebRtcIlbcfix_DoThePlc(PLCresidual, PLClpc, 1, decresidual, syntdenum,
-                           (int16_t)(iLBCdec_inst->last_lag), iLBCdec_inst);
+                           iLBCdec_inst->last_lag, iLBCdec_inst);
 
     WEBRTC_SPL_MEMCPY_W16(decresidual, PLCresidual, iLBCdec_inst->blockl);
 
@@ -188,18 +188,18 @@
     WEBRTC_SPL_MEMCPY_W16(iLBCdec_inst->syntMem, &data[iLBCdec_inst->blockl-LPC_FILTERORDER], LPC_FILTERORDER);
 
   } else { /* Enhancer not activated */
-    int16_t lag;
+    size_t lag;
 
     /* Find last lag (since the enhancer is not called to give this info) */
     lag = 20;
     if (iLBCdec_inst->mode==20) {
-      lag = (int16_t)WebRtcIlbcfix_XcorrCoef(
+      lag = WebRtcIlbcfix_XcorrCoef(
           &decresidual[iLBCdec_inst->blockl-60],
           &decresidual[iLBCdec_inst->blockl-60-lag],
           60,
           80, lag, -1);
     } else {
-      lag = (int16_t)WebRtcIlbcfix_XcorrCoef(
+      lag = WebRtcIlbcfix_XcorrCoef(
           &decresidual[iLBCdec_inst->blockl-ENH_BLOCKL],
           &decresidual[iLBCdec_inst->blockl-ENH_BLOCKL-lag],
           ENH_BLOCKL,