AgcManagerDirect unit tests refactoring

Stop using TEST_F; that will make it easier to switch to parametric
tests that are needed to correctly test `AgcManagerDirect`.

"Avoid fixtures where reasonable."
Source: https://abseil.io/tips/122

Bug: chromium:1275566
Change-Id: I2d73a0913eb2349144f63bd17ab4d6efa245e472
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/268766
Reviewed-by: Hanna Silen <silen@webrtc.org>
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#37556}

modules/audio_processing/agc/agc_manager_direct.cc

@@ -448,10 +448,10 @@ AgcManagerDirect::AgcManagerDirect(
     float clipped_ratio_threshold,
     int clipped_wait_frames,
     const ClippingPredictorConfig& clipping_config)
-    : AgcManagerDirect(/*num_capture_channels*/ 1,
+    : AgcManagerDirect(/*num_capture_channels=*/1,
                        startup_min_level,
                        clipped_level_min,
-                       /*disable_digital_adaptive*/ false,
+                       /*disable_digital_adaptive=*/false,
                        clipped_level_step,
                        clipped_ratio_threshold,
                        clipped_wait_frames,

modules/audio_processing/agc/agc_manager_direct.h

@@ -86,29 +86,27 @@ class AgcManagerDirect final {
   }
 
  private:
-  friend class AgcManagerDirectTest;
+  friend class AgcManagerDirectTestHelper;
 
-  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectStandaloneTest,
-                           DisableDigitalDisablesDigital);
-  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectStandaloneTest,
+  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectTest, DisableDigitalDisablesDigital);
+  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectTest,
                            AgcMinMicLevelExperimentDefault);
-  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectStandaloneTest,
+  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectTest,
                            AgcMinMicLevelExperimentDisabled);
-  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectStandaloneTest,
+  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectTest,
                            AgcMinMicLevelExperimentOutOfRangeAbove);
-  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectStandaloneTest,
+  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectTest,
                            AgcMinMicLevelExperimentOutOfRangeBelow);
-  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectStandaloneTest,
+  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectTest,
                            AgcMinMicLevelExperimentEnabled50);
-  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectStandaloneTest,
+  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectTest,
                            AgcMinMicLevelExperimentEnabledAboveStartupLevel);
-  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectStandaloneTest,
-                           ClippingParametersVerified);
-  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectStandaloneTest,
+  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectTest, ClippingParametersVerified);
+  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectTest,
                            DisableClippingPredictorDoesNotLowerVolume);
-  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectStandaloneTest,
+  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectTest,
                            UsedClippingPredictionsProduceLowerAnalogLevels);
-  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectStandaloneTest,
+  FRIEND_TEST_ALL_PREFIXES(AgcManagerDirectTest,
                            UnusedClippingPredictionsProduceEqualAnalogLevels);
 
   // Dependency injection for testing. Don't delete `agc` as the memory is owned