Simplify (less verbose) filter notation

Bug: webrtc:417439718
Change-Id: I43681a1e0c3926993f81c957f93a6b0a285dedfd
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/391440
Commit-Queue: Gustaf Ullberg <gustaf@webrtc.org>
Reviewed-by: Sam Zackrisson <saza@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#44623}
diff --git a/modules/audio_processing/aec3/adaptive_fir_filter_unittest.cc b/modules/audio_processing/aec3/adaptive_fir_filter_unittest.cc
index 0d5eef6..387a074 100644
--- a/modules/audio_processing/aec3/adaptive_fir_filter_unittest.cc
+++ b/modules/audio_processing/aec3/adaptive_fir_filter_unittest.cc
@@ -513,8 +513,8 @@
   std::array<float, kFftLengthBy2Plus1> E2_coarse;
   // [B,A] = butter(2,100/8000,'high')
   constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 1>
-      kHighPassFilterCoefficients = {CascadedBiQuadFilter::BiQuadCoefficients{
-          {0.97261f, -1.94523f, 0.97261f}, {-1.94448f, 0.94598f}}};
+      kHighPassFilterCoefficients = {
+          {{{0.97261f, -1.94523f, 0.97261f}, {-1.94448f, 0.94598f}}}};
   for (auto& Y2_ch : Y2) {
     Y2_ch.fill(0.f);
   }
diff --git a/modules/audio_processing/aec3/subtractor_unittest.cc b/modules/audio_processing/aec3/subtractor_unittest.cc
index d348532..d940df4 100644
--- a/modules/audio_processing/aec3/subtractor_unittest.cc
+++ b/modules/audio_processing/aec3/subtractor_unittest.cc
@@ -99,8 +99,8 @@
 
   // [B,A] = butter(2,100/8000,'high')
   constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 1>
-      kHighPassFilterCoefficients = {CascadedBiQuadFilter::BiQuadCoefficients{
-          {0.97261f, -1.94523f, 0.97261f}, {-1.94448f, 0.94598f}}};
+      kHighPassFilterCoefficients = {
+          {{{0.97261f, -1.94523f, 0.97261f}, {-1.94448f, 0.94598f}}}};
   std::vector<std::unique_ptr<CascadedBiQuadFilter>> x_hp_filter(
       num_render_channels);
   for (size_t ch = 0; ch < num_render_channels; ++ch) {
diff --git a/modules/audio_processing/high_pass_filter.cc b/modules/audio_processing/high_pass_filter.cc
index a6c2154..276b5a2 100644
--- a/modules/audio_processing/high_pass_filter.cc
+++ b/modules/audio_processing/high_pass_filter.cc
@@ -25,23 +25,20 @@
 // [B,A] = butter(2,100/8000,'high')
 constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 1>
     kHighPassFilterCoefficients16kHz = {
-        CascadedBiQuadFilter::BiQuadCoefficients{
-            {0.972613898f, -1.945227797f, 0.972613898f},
-            {-1.944477658f, 0.945977936f}}};
+        {{{0.972613898f, -1.945227797f, 0.972613898f},
+          {-1.944477658f, 0.945977936f}}}};
 
 // [B,A] = butter(2,100/16000,'high')
 constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 1>
     kHighPassFilterCoefficients32kHz = {
-        CascadedBiQuadFilter::BiQuadCoefficients{
-            {0.986211925f, -1.972423849f, 0.986211925f},
-            {-1.972233729f, 0.972613969f}}};
+        {{{0.986211925f, -1.972423849f, 0.986211925f},
+          {-1.972233729f, 0.972613969f}}}};
 
 // [B,A] = butter(2,100/24000,'high')
 constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 1>
     kHighPassFilterCoefficients48kHz = {
-        CascadedBiQuadFilter::BiQuadCoefficients{
-            {0.990786698f, -1.981573396f, 0.990786698f},
-            {-1.981488509f, 0.981658283f}}};
+        {{{0.990786698f, -1.981573396f, 0.990786698f},
+          {-1.981488509f, 0.981658283f}}}};
 
 ArrayView<const CascadedBiQuadFilter::BiQuadCoefficients> ChooseCoefficients(
     int sample_rate_hz) {
diff --git a/modules/audio_processing/utility/cascaded_biquad_filter_unittest.cc b/modules/audio_processing/utility/cascaded_biquad_filter_unittest.cc
index b83f4aa..cf21378 100644
--- a/modules/audio_processing/utility/cascaded_biquad_filter_unittest.cc
+++ b/modules/audio_processing/utility/cascaded_biquad_filter_unittest.cc
@@ -25,22 +25,18 @@
 // Coefficients for a second order Butterworth high-pass filter with cutoff
 // frequency 100 Hz.
 constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 1>
-    kHighPassFilterCoefficients = {CascadedBiQuadFilter::BiQuadCoefficients{
-        {0.97261f, -1.94523f, 0.97261f},
-        {-1.94448f, 0.94598f}}};
+    kHighPassFilterCoefficients = {
+        {{{0.97261f, -1.94523f, 0.97261f}, {-1.94448f, 0.94598f}}}};
 
 constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 1>
-    kTransparentCoefficients = {
-        CascadedBiQuadFilter::BiQuadCoefficients{{1.f, 0.f, 0.f}, {0.f, 0.f}}};
+    kTransparentCoefficients = {{{{1.f, 0.f, 0.f}, {0.f, 0.f}}}};
 
 constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 1>
-    kBlockingCoefficients = {
-        CascadedBiQuadFilter::BiQuadCoefficients{{0.f, 0.f, 0.f}, {0.f, 0.f}}};
+    kBlockingCoefficients = {{{{0.f, 0.f, 0.f}, {0.f, 0.f}}}};
 
 constexpr std::array<CascadedBiQuadFilter::BiQuadCoefficients, 2>
     kCascadedCoefficients = {
-        CascadedBiQuadFilter::BiQuadCoefficients{{-1.f, 0.f, 0.f}, {0.f, 0.f}},
-        CascadedBiQuadFilter::BiQuadCoefficients{{0.f, 0.f, -1.f}, {0.f, 0.f}}};
+        {{{-1.f, 0.f, 0.f}, {0.f, 0.f}}, {{0.f, 0.f, -1.f}, {0.f, 0.f}}}};
 
 std::vector<float> CreateInputWithIncreasingValues(size_t vector_length) {
   std::vector<float> v(vector_length);