Reland "Upconvert various types to int.", neteq portion.

This reverts portions of commit cb180976dd0e9672cde4523d87b5f4857478b5e9, which
reverted commit 83ad33a8aed1fb00e422b6abd33c3e8942821c24.  Specifically, the
files in webrtc/modules/audio_coding/neteq/ are relanded.

The original commit message is below:

Upconvert various types to int.

Per comments from HL/kwiberg on https://webrtc-codereview.appspot.com/42569004 , when there is existing usage of mixed types (int16_t, int, etc.), we'd prefer to standardize on larger types like int and phase out use of int16_t.

Specifically, "Using int16 just because we're sure all reasonable values will fit in 16 bits isn't usually meaningful in C."

This converts some existing uses of int16_t (and, in a few cases, other types such as uint16_t) to int (or, in a few places, int32_t).  Other locations will be converted to size_t in a separate change.

BUG=none
TBR=kwiberg

Review URL: https://codereview.webrtc.org/1181073002

Cr-Commit-Position: refs/heads/master@{#9427}
diff --git a/webrtc/modules/audio_coding/neteq/expand.cc b/webrtc/modules/audio_coding/neteq/expand.cc
index bde6559..10f6a9f 100644
--- a/webrtc/modules/audio_coding/neteq/expand.cc
+++ b/webrtc/modules/audio_coding/neteq/expand.cc
@@ -239,14 +239,12 @@
     if (consecutive_expands_ == 3) {
       // Let the mute factor decrease from 1.0 to 0.95 in 6.25 ms.
       // mute_slope = 0.0010 / fs_mult in Q20.
-      parameters.mute_slope = std::max(parameters.mute_slope,
-                                       static_cast<int16_t>(1049 / fs_mult));
+      parameters.mute_slope = std::max(parameters.mute_slope, 1049 / fs_mult);
     }
     if (consecutive_expands_ == 7) {
       // Let the mute factor decrease from 1.0 to 0.90 in 6.25 ms.
       // mute_slope = 0.0020 / fs_mult in Q20.
-      parameters.mute_slope = std::max(parameters.mute_slope,
-                                       static_cast<int16_t>(2097 / fs_mult));
+      parameters.mute_slope = std::max(parameters.mute_slope, 2097 / fs_mult);
     }
 
     // Mute segment according to slope value.
@@ -368,7 +366,7 @@
   InitializeForAnExpandPeriod();
 
   // Calculate correlation in downsampled domain (4 kHz sample rate).
-  int16_t correlation_scale;
+  int correlation_scale;
   int correlation_length = 51;  // TODO(hlundin): Legacy bit-exactness.
   // If it is decided to break bit-exactness |correlation_length| should be
   // initialized to the return value of Correlation().
@@ -445,7 +443,7 @@
                        correlation_length + start_index + correlation_lags - 1);
     correlation_scale = ((31 - WebRtcSpl_NormW32(signal_max * signal_max))
         + (31 - WebRtcSpl_NormW32(correlation_length))) - 31;
-    correlation_scale = std::max(static_cast<int16_t>(0), correlation_scale);
+    correlation_scale = std::max(0, correlation_scale);
 
     // Calculate the correlation, store in |correlation_vector2|.
     WebRtcSpl_CrossCorrelation(
@@ -472,7 +470,7 @@
 
     // Calculate the correlation coefficient between the two portions of the
     // signal.
-    int16_t corr_coefficient;
+    int32_t corr_coefficient;
     if ((energy1 > 0) && (energy2 > 0)) {
       int energy1_scale = std::max(16 - WebRtcSpl_NormW32(energy1), 0);
       int energy2_scale = std::max(16 - WebRtcSpl_NormW32(energy2), 0);
@@ -481,17 +479,17 @@
         // If sum is odd, add 1 to make it even.
         energy1_scale += 1;
       }
-      int16_t scaled_energy1 = energy1 >> energy1_scale;
-      int16_t scaled_energy2 = energy2 >> energy2_scale;
-      int16_t sqrt_energy_product = WebRtcSpl_SqrtFloor(
-          scaled_energy1 * scaled_energy2);
+      int32_t scaled_energy1 = energy1 >> energy1_scale;
+      int32_t scaled_energy2 = energy2 >> energy2_scale;
+      int16_t sqrt_energy_product = static_cast<int16_t>(
+          WebRtcSpl_SqrtFloor(scaled_energy1 * scaled_energy2));
       // Calculate max_correlation / sqrt(energy1 * energy2) in Q14.
       int cc_shift = 14 - (energy1_scale + energy2_scale) / 2;
       max_correlation = WEBRTC_SPL_SHIFT_W32(max_correlation, cc_shift);
       corr_coefficient = WebRtcSpl_DivW32W16(max_correlation,
                                              sqrt_energy_product);
-      corr_coefficient = std::min(static_cast<int16_t>(16384),
-                                  corr_coefficient);  // Cap at 1.0 in Q14.
+      // Cap at 1.0 in Q14.
+      corr_coefficient = std::min(16384, corr_coefficient);
     } else {
       corr_coefficient = 0;
     }
@@ -512,8 +510,8 @@
     if ((energy1 / 4 < energy2) && (energy1 > energy2 / 4)) {
       // Energy constraint fulfilled. Use both vectors and scale them
       // accordingly.
-      int16_t scaled_energy2 = std::max(16 - WebRtcSpl_NormW32(energy2), 0);
-      int16_t scaled_energy1 = scaled_energy2 - 13;
+      int32_t scaled_energy2 = std::max(16 - WebRtcSpl_NormW32(energy2), 0);
+      int32_t scaled_energy1 = scaled_energy2 - 13;
       // Calculate scaled_energy1 / scaled_energy2 in Q13.
       int32_t energy_ratio = WebRtcSpl_DivW32W16(
           WEBRTC_SPL_SHIFT_W32(energy1, -scaled_energy1),
@@ -682,7 +680,8 @@
     //   voice_mix_factor = 0;
     if (corr_coefficient > 7875) {
       int16_t x1, x2, x3;
-      x1 = corr_coefficient;  // |corr_coefficient| is in Q14.
+      // |corr_coefficient| is in Q14.
+      x1 = static_cast<int16_t>(corr_coefficient);
       x2 = (x1 * x1) >> 14;   // Shift 14 to keep result in Q14.
       x3 = (x1 * x2) >> 14;
       static const int kCoefficients[4] = { -5179, 19931, -16422, 5776 };
@@ -709,7 +708,7 @@
       // the division.
       // Shift the denominator from Q13 to Q5 before the division. The result of
       // the division will then be in Q20.
-      int16_t temp_ratio = WebRtcSpl_DivW32W16(
+      int temp_ratio = WebRtcSpl_DivW32W16(
           (slope - 8192) << 12,
           static_cast<int16_t>((distortion_lag * slope) >> 8));
       if (slope > 14746) {
@@ -730,8 +729,7 @@
         // Make sure the mute factor decreases from 1.0 to 0.9 in no more than
         // 6.25 ms.
         // mute_slope >= 0.005 / fs_mult in Q20.
-        parameters.mute_slope = std::max(static_cast<int16_t>(5243 / fs_mult),
-                                         parameters.mute_slope);
+        parameters.mute_slope = std::max(5243 / fs_mult, parameters.mute_slope);
       } else if (slope > 8028) {
         parameters.mute_slope = 0;
       }
@@ -755,7 +753,7 @@
 void Expand::Correlation(const int16_t* input,
                          size_t input_length,
                          int16_t* output,
-                         int16_t* output_scale) const {
+                         int* output_scale) const {
   // Set parameters depending on sample rate.
   const int16_t* filter_coefficients;
   int16_t num_coefficients;
@@ -844,7 +842,7 @@
 // TODO(turajs): This can be moved to BackgroundNoise class.
 void Expand::GenerateBackgroundNoise(int16_t* random_vector,
                                      size_t channel,
-                                     int16_t mute_slope,
+                                     int mute_slope,
                                      bool too_many_expands,
                                      size_t num_noise_samples,
                                      int16_t* buffer) {
@@ -887,7 +885,7 @@
         bgn_mute_factor > 0) {
       // Fade BGN to zero.
       // Calculate muting slope, approximately -2^18 / fs_hz.
-      int16_t mute_slope;
+      int mute_slope;
       if (fs_hz_ == 8000) {
         mute_slope = -32;
       } else if (fs_hz_ == 16000) {