CSS: Use count position values with 3 parts

third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp

Index: third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp
diff --git a/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp b/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp
index e29b3bc6b9d72f12275fb08782efe52e328bda78..d94d66bb67f0bd890cd8e003705937312e4aab45 100644
--- a/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp
+++ b/third_party/WebKit/Source/core/css/parser/CSSPropertyParser.cpp
@@ -1646,10 +1646,30 @@ const CSSValue* CSSPropertyParser::ParseSingleValue(
     case CSSPropertyWebkitLogicalWidth:
     case CSSPropertyWebkitLogicalHeight:
       return CSSPropertyLengthUtils::ConsumeWidthOrHeight(range_, *context_);
-    case CSSPropertyScrollSnapDestination:
-    case CSSPropertyObjectPosition:
-    case CSSPropertyPerspectiveOrigin:
-      return ConsumePosition(range_, context_->Mode(), UnitlessQuirk::kForbid);
+    case CSSPropertyScrollSnapDestination: {
+      // TODO(crbug.com/724912): Retire scroll-snap-destination
+      auto syntax =
+          CSSPropertyParserHelpers::PositionSyntax::kPermitThreeValues;
+      return ConsumePosition(range_, *context_, UnitlessQuirk::kForbid, syntax);
+    }
+    case CSSPropertyObjectPosition: {
+      auto syntax =
+          CSSPropertyParserHelpers::PositionSyntax::kPermitThreeValues;
+      const CSSValue* result =
+          ConsumePosition(range_, *context_, UnitlessQuirk::kForbid, syntax);
+      if (syntax == CSSPropertyParserHelpers::PositionSyntax::kCountThreeValues)
+        context_->Count(UseCounter::kThreeValuedPositionObjectPosition);
+      return result;
+    }
+    case CSSPropertyPerspectiveOrigin: {
+      auto syntax =
+          CSSPropertyParserHelpers::PositionSyntax::kPermitThreeValues;
+      const CSSValue* result =
+          ConsumePosition(range_, *context_, UnitlessQuirk::kForbid, syntax);
+      if (syntax == CSSPropertyParserHelpers::PositionSyntax::kCountThreeValues)
+        context_->Count(UseCounter::kThreeValuedPositionPerspectiveOrigin);
+      return result;
+    }
     case CSSPropertyWebkitHyphenateCharacter:
     case CSSPropertyWebkitLocale:
       return ConsumeLocale(range_);
@@ -2610,9 +2630,12 @@ static bool ConsumeBackgroundPosition(CSSParserTokenRange& range,
   do {
     CSSValue* position_x = nullptr;
     CSSValue* position_y = nullptr;
-    if (!ConsumePosition(range, context->Mode(), unitless, position_x,
+    auto syntax = CSSPropertyParserHelpers::PositionSyntax::kPermitThreeValues;
+    if (!ConsumePosition(range, *context, unitless, syntax, position_x,
                          position_y))
       return false;
+    if (syntax == CSSPropertyParserHelpers::PositionSyntax::kCountThreeValues)
+      context->Count(UseCounter::kThreeValuedPositionBackground);
     AddBackgroundValue(result_x, position_x);
     AddBackgroundValue(result_y, position_y);
   } while (ConsumeCommaIncludingWhitespace(range));
@@ -2691,9 +2714,14 @@ bool CSSPropertyParser::ConsumeBackgroundShorthand(
           ConsumeRepeatStyleComponent(range_, value, value_y, implicit);
         } else if (property == CSSPropertyBackgroundPositionX ||
                    property == CSSPropertyWebkitMaskPositionX) {
-          if (!ConsumePosition(range_, context_->Mode(), UnitlessQuirk::kForbid,
-                               value, value_y))
+          auto syntax =
+              CSSPropertyParserHelpers::PositionSyntax::kPermitThreeValues;
+          if (!ConsumePosition(range_, *context_, UnitlessQuirk::kForbid,
+                               syntax, value, value_y))
             continue;
+          if (syntax ==
+              CSSPropertyParserHelpers::PositionSyntax::kCountThreeValues)
+            context_->Count(UseCounter::kThreeValuedPositionBackground);
         } else if (property == CSSPropertyBackgroundSize ||
                    property == CSSPropertyWebkitMaskSize) {
           if (!ConsumeSlashIncludingWhitespace(range_))