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/neteq/neteq_impl.h b/webrtc/modules/audio_coding/neteq/neteq_impl.h
index 55ba067..502204a 100644
--- a/webrtc/modules/audio_coding/neteq/neteq_impl.h
+++ b/webrtc/modules/audio_coding/neteq/neteq_impl.h
@@ -106,7 +106,7 @@
   // Returns kOK on success, or kFail in case of an error.
   int GetAudio(size_t max_length,
                int16_t* output_audio,
-               int* samples_per_channel,
+               size_t* samples_per_channel,
                int* num_channels,
                NetEqOutputType* type) override;
 
@@ -203,9 +203,9 @@
 
  protected:
   static const int kOutputSizeMs = 10;
-  static const int kMaxFrameSize = 2880;  // 60 ms @ 48 kHz.
+  static const size_t kMaxFrameSize = 2880;  // 60 ms @ 48 kHz.
   // TODO(hlundin): Provide a better value for kSyncBufferSize.
-  static const int kSyncBufferSize = 2 * kMaxFrameSize;
+  static const size_t kSyncBufferSize = 2 * kMaxFrameSize;
 
   // Inserts a new packet into NetEq. This is used by the InsertPacket method
   // above. Returns 0 on success, otherwise an error code.
@@ -225,7 +225,7 @@
   // Returns 0 on success, otherwise an error code.
   int GetAudioInternal(size_t max_length,
                        int16_t* output,
-                       int* samples_per_channel,
+                       size_t* samples_per_channel,
                        int* num_channels) EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
 
   // Provides a decision to the GetAudioInternal method. The decision what to
@@ -318,7 +318,7 @@
   // |required_samples| samples. The packets are inserted into |packet_list|.
   // Returns the number of samples that the packets in the list will produce, or
   // -1 in case of an error.
-  int ExtractPackets(int required_samples, PacketList* packet_list)
+  int ExtractPackets(size_t required_samples, PacketList* packet_list)
       EXCLUSIVE_LOCKS_REQUIRED(crit_sect_);
 
   // Resets various variables and objects to new values based on the sample rate
@@ -375,8 +375,8 @@
   StatisticsCalculator stats_ GUARDED_BY(crit_sect_);
   int fs_hz_ GUARDED_BY(crit_sect_);
   int fs_mult_ GUARDED_BY(crit_sect_);
-  int output_size_samples_ GUARDED_BY(crit_sect_);
-  int decoder_frame_length_ GUARDED_BY(crit_sect_);
+  size_t output_size_samples_ GUARDED_BY(crit_sect_);
+  size_t decoder_frame_length_ GUARDED_BY(crit_sect_);
   Modes last_mode_ GUARDED_BY(crit_sect_);
   rtc::scoped_ptr<int16_t[]> mute_factor_array_ GUARDED_BY(crit_sect_);
   size_t decoded_buffer_length_ GUARDED_BY(crit_sect_);