Deprecate step timing with position 'middle'

third_party/WebKit/Source/core/frame/Deprecation.cpp

Index: third_party/WebKit/Source/core/frame/Deprecation.cpp
diff --git a/third_party/WebKit/Source/core/frame/Deprecation.cpp b/third_party/WebKit/Source/core/frame/Deprecation.cpp
index ba6b0bc2c1be874de89a9e20071e6d359df6fa66..8a1909300966c3a2c77a69292dd1ca63af1c5553 100644
--- a/third_party/WebKit/Source/core/frame/Deprecation.cpp
+++ b/third_party/WebKit/Source/core/frame/Deprecation.cpp
@@ -440,6 +440,11 @@ String Deprecation::DeprecationMessage(WebFeature feature) {
           "the CredentialsContainer.preventSilentAccess method", M62,
           "4781762488041472");
 
+    case WebFeature::kDeprecatedTimingFunctionStepMiddle:
+      return replacedWillBeRemoved(
+          "The step timing function with step position 'middle'",
+          "the frames timing function", M62, "5189363944128512");
+
     // Features that aren't deprecated don't have a deprecation message.
     default:
       return String();