Deprecate step timing with position 'middle'

third_party/WebKit/public/platform/WebFeature.h

 #ifndef WebFeature_h
 #define WebFeature_h
 
 namespace blink {
 // ============ Definition for WebFeature used for UseCounter ===============
 //
 // Do not change assigned numbers of existing items: add new features
 // to the end of the list.
 //
 // A WebFeature conceptually represents some particular web-exposed API
@@ skipping 1540 matching lines @@
   kTableSectionDirectionDifferentFromTable = 2016,
   // The above items are available in M60 branch.
 
   kClientHintsDeviceRAM = 2017,
   kCSSRegisterProperty = 2018,
   kRelativeOrientationSensorConstructor = 2019,
   kSmoothScrollJSInterventionActivated = 2020,
   kBudgetAPIGetCost = 2021,
   kBudgetAPIGetBudget = 2022,
   kCrossOriginMainFrameNulledNonEmptyNameAccessed = 2023,
+  kDeprecatedTimingFunctionStepMiddle = 2024,
 
   // Add new features immediately above this line. Don't change assigned
   // numbers of any item, and don't reuse removed slots.
   // Also, run update_use_counter_feature_enum.py in
   // chromium/src/tools/metrics/histograms/ to update the UMA mapping.
   kNumberOfFeatures,  // This enum value must be last.
 };
 
 }  // namespace blink
 
 #endif  // WebFeature_h