Revert of Use an explicit identifier in Config

webrtc/modules/audio_processing/include/audio_processing.h

Index: webrtc/modules/audio_processing/include/audio_processing.h
diff --git a/webrtc/modules/audio_processing/include/audio_processing.h b/webrtc/modules/audio_processing/include/audio_processing.h
index 14d7de30434a6f85ba29a9d043e2b4587f7bbe85..5fcc4d4672965b6ea3c3fe0cf57860259c1551cd 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -65,7 +65,6 @@
 struct ExtendedFilter {
   ExtendedFilter() : enabled(false) {}
   explicit ExtendedFilter(bool enabled) : enabled(enabled) {}
-  static const ConfigOptionID identifier = ConfigOptionID::kExtendedFilter;
   bool enabled;
 };
 
@@ -77,7 +76,6 @@
 struct DelayAgnostic {
   DelayAgnostic() : enabled(false) {}
   explicit DelayAgnostic(bool enabled) : enabled(enabled) {}
-  static const ConfigOptionID identifier = ConfigOptionID::kDelayAgnostic;
   bool enabled;
 };
 
@@ -98,7 +96,6 @@
       : enabled(enabled), startup_min_volume(kAgcStartupMinVolume) {}
   ExperimentalAgc(bool enabled, int startup_min_volume)
       : enabled(enabled), startup_min_volume(startup_min_volume) {}
-  static const ConfigOptionID identifier = ConfigOptionID::kExperimentalAgc;
   bool enabled;
   int startup_min_volume;
 };
@@ -108,7 +105,6 @@
 struct ExperimentalNs {
   ExperimentalNs() : enabled(false) {}
   explicit ExperimentalNs(bool enabled) : enabled(enabled) {}
-  static const ConfigOptionID identifier = ConfigOptionID::kExperimentalNs;
   bool enabled;
 };
 
@@ -131,7 +127,6 @@
       : enabled(enabled),
         array_geometry(array_geometry),
         target_direction(target_direction) {}
-  static const ConfigOptionID identifier = ConfigOptionID::kBeamforming;
   const bool enabled;
   const std::vector<Point> array_geometry;
   const SphericalPointf target_direction;
@@ -146,7 +141,6 @@
 struct Intelligibility {
   Intelligibility() : enabled(false) {}
   explicit Intelligibility(bool enabled) : enabled(enabled) {}
-  static const ConfigOptionID identifier = ConfigOptionID::kIntelligibility;
   bool enabled;
 };