CSS: retire use count :not with invalid selectors

This reverts the use counters added in
https://chromium-review.googlesource.com/c/chromium/src/+/1354751

The CSS Working Group was considering allowing :not() to
ignore selectors that are invalid or not accepted by the browser.

Use counts showed that this would affect a large percentage of pages
https://github.com/w3c/csswg-drafts/issues/3264#issuecomment-463036664
and so the decision was made to not change the behavior of :not
https://github.com/w3c/csswg-drafts/issues/3264#issuecomment-467190906

Data collection is no longer required.

BUG=568705

Change-Id: I38ddaee5339e19b70c1c13c9507a50ae27c354b0
Reviewed-on: https://chromium-review.googlesource.com/c/1487753
Commit-Queue: Emil A Eklund <eae@chromium.org>
Reviewed-by: Emil A Eklund <eae@chromium.org>
Cr-Commit-Position: refs/heads/master@{#635559}

third_party/blink/public/platform/web_feature.mojom

@@ -2077,9 +2077,6 @@ enum WebFeature {
   kFlexboxSingleLineAlignContent = 2642,
   kSignedExchangeInnerResponseInMainFrame = 2643,
   kSignedExchangeInnerResponseInSubFrame = 2644,
-  kCSSSelectorNotWithValidList = 2645,
-  kCSSSelectorNotWithInvalidList = 2646,
-  kCSSSelectorNotWithPartiallyValidList = 2647,
   // The above items are available in M72 branch.
 
   kV8IDBFactory_Databases_Method = 2648,

third_party/blink/renderer/core/css/parser/css_selector_parser.cc

@@ -495,44 +495,6 @@ std::unique_ptr<CSSParserSelector> CSSSelectorParser::ConsumeAttribute(
   return selector;
 }
 
-void CSSSelectorParser::CountRejectedNot(CSSParserTokenRange& range) {
-  bool exists_valid = false;
-  bool exists_invalid = false;
-
-  do {
-    if (exists_valid || exists_invalid) {
-      DCHECK(range.Peek().GetType() == kCommaToken);
-      range.ConsumeIncludingWhitespace();
-    }
-    // else we are parsing the first complex selector
-
-    failed_parsing_ = false;
-    bool consumed_invalid = !ConsumeComplexSelector(range) || failed_parsing_;
-    range.ConsumeWhitespace();
-    while (!range.AtEnd() && range.Peek().GetType() != kCommaToken) {
-      consumed_invalid = true;
-      range.ConsumeIncludingWhitespace();
-    }
-
-    if (consumed_invalid)
-      exists_invalid = true;
-    else
-      exists_valid = true;
-  } while (!range.AtEnd());
-
-  WebFeature feature;
-  if (exists_valid) {
-    if (exists_invalid)
-      feature = WebFeature::kCSSSelectorNotWithPartiallyValidList;
-    else
-      feature = WebFeature::kCSSSelectorNotWithValidList;
-  } else {
-    feature = WebFeature::kCSSSelectorNotWithInvalidList;
-  }
-  context_->Count(feature);
-  failed_parsing_ = true;
-}
-
 std::unique_ptr<CSSParserSelector> CSSSelectorParser::ConsumePseudo(
     CSSParserTokenRange& range) {
   DCHECK_EQ(range.Peek().GetType(), kColonToken);
@@ -623,17 +585,11 @@ std::unique_ptr<CSSParserSelector> CSSSelectorParser::ConsumePseudo(
       return selector;
     }
     case CSSSelector::kPseudoNot: {
-      CSSParserTokenRange fallback_block = block;
-
       std::unique_ptr<CSSParserSelector> inner_selector =
           ConsumeCompoundSelector(block);
       block.ConsumeWhitespace();
-      if (!inner_selector || !inner_selector->IsSimple() ||
-          inner_selector->Relation() != CSSSelector::kSubSelector ||
-          !block.AtEnd()) {
-        CountRejectedNot(fallback_block);
+      if (!inner_selector || !inner_selector->IsSimple() || !block.AtEnd())
         return nullptr;
-      }
       Vector<std::unique_ptr<CSSParserSelector>> selector_vector;
       selector_vector.push_back(std::move(inner_selector));
       selector->AdoptSelectorVector(selector_vector);

third_party/blink/renderer/core/css/parser/css_selector_parser.h

@@ -80,7 +80,6 @@ class CORE_EXPORT CSSSelectorParser {
   SplitCompoundAtImplicitShadowCrossingCombinator(
       std::unique_ptr<CSSParserSelector> compound_selector);
   void RecordUsageAndDeprecations(const CSSSelectorList&);
-  void CountRejectedNot(CSSParserTokenRange&);
 
   Member<const CSSParserContext> context_;
   Member<const StyleSheetContents> style_sheet_;

third_party/blink/renderer/core/css/parser/css_selector_parser_test.cc

@@ -792,88 +792,4 @@ TEST(CSSSelectorParserTest, ImplicitShadowCrossingCombinators) {
   }
 }
 
-TEST(CSSSelectorParserTest, UseCountRejectedNot) {
-  auto ExpectCount = [](const char* selector, WebFeature feature) {
-    std::unique_ptr<DummyPageHolder> dummy_holder =
-        DummyPageHolder::Create(IntSize(500, 500));
-    Document* doc = &dummy_holder->GetDocument();
-    Page::InsertOrdinaryPageForTesting(&dummy_holder->GetPage());
-    CSSParserContext* context = CSSParserContext::Create(
-        kHTMLStandardMode, SecureContextMode::kSecureContext,
-        CSSParserContext::kLiveProfile, doc);
-    StyleSheetContents* sheet = StyleSheetContents::Create(context);
-    EXPECT_FALSE(UseCounter::IsCounted(*doc, feature));
-
-    CSSTokenizer tokenizer(selector);
-    const auto tokens = tokenizer.TokenizeToEOF();
-    CSSParserTokenRange range(tokens);
-    CSSSelectorParser::ParseSelector(range, context, sheet);
-
-    bool result = UseCounter::IsCounted(*doc, feature);
-    EXPECT_TRUE(result);
-  };
-
-  ExpectCount(":not(:nonsense :gibberish)",
-              WebFeature::kCSSSelectorNotWithInvalidList);
-  ExpectCount(":not(:nonsense :gibberish, .a)",
-              WebFeature::kCSSSelectorNotWithPartiallyValidList);
-  ExpectCount(":not()", WebFeature::kCSSSelectorNotWithInvalidList);
-  ExpectCount(":not(,)", WebFeature::kCSSSelectorNotWithInvalidList);
-  ExpectCount(":not(,,)", WebFeature::kCSSSelectorNotWithInvalidList);
-  ExpectCount(":not(* .a)", WebFeature::kCSSSelectorNotWithValidList);
-  ExpectCount(":not(:nonsense)", WebFeature::kCSSSelectorNotWithInvalidList);
-  ExpectCount(":not(* * .previouslyFailed)",
-              WebFeature::kCSSSelectorNotWithValidList);
-  ExpectCount(":not(* :nonsense)", WebFeature::kCSSSelectorNotWithInvalidList);
-  ExpectCount(":not(:nonsense *)", WebFeature::kCSSSelectorNotWithInvalidList);
-  ExpectCount(":not(*,)", WebFeature::kCSSSelectorNotWithPartiallyValidList);
-  ExpectCount(":not(*,,)", WebFeature::kCSSSelectorNotWithPartiallyValidList);
-  ExpectCount(":not(:nonsense ,)", WebFeature::kCSSSelectorNotWithInvalidList);
-  ExpectCount(":not(:nonsense,,)", WebFeature::kCSSSelectorNotWithInvalidList);
-  ExpectCount(":not(*, *)", WebFeature::kCSSSelectorNotWithValidList);
-  ExpectCount(":not(*, :nonsense)",
-              WebFeature::kCSSSelectorNotWithPartiallyValidList);
-  ExpectCount(":not(* , * *)", WebFeature::kCSSSelectorNotWithValidList);
-  ExpectCount(":not(*, * :nonsense)",
-              WebFeature::kCSSSelectorNotWithPartiallyValidList);
-  ExpectCount(":not(:nonsense,*)",
-              WebFeature::kCSSSelectorNotWithPartiallyValidList);
-  ExpectCount(":not(:nonsense , :nonsense)",
-              WebFeature::kCSSSelectorNotWithInvalidList);
-  ExpectCount(":not(:nonsense, * *)",
-              WebFeature::kCSSSelectorNotWithPartiallyValidList);
-  ExpectCount(":not(:nonsense, * :nonsense )",
-              WebFeature::kCSSSelectorNotWithInvalidList);
-  ExpectCount(":not(*, :not(* * :nonsense))",
-              WebFeature::kCSSSelectorNotWithPartiallyValidList);
-  ExpectCount(":not(:not(* * :nonsense) , *)",
-              WebFeature::kCSSSelectorNotWithPartiallyValidList);
-  ExpectCount(":not(.a || :nonsense, *)",
-              WebFeature::kCSSSelectorNotWithPartiallyValidList);
-}
-
-TEST(CSSSelectorParserTest, SimpleNotNeverCounted) {
-  // :not with a simple selector from CSS Selectors 3 is not counted.
-  std::unique_ptr<DummyPageHolder> dummy_holder =
-      DummyPageHolder::Create(IntSize(500, 500));
-  Document* doc = &dummy_holder->GetDocument();
-  Page::InsertOrdinaryPageForTesting(&dummy_holder->GetPage());
-  CSSParserContext* context = CSSParserContext::Create(
-      kHTMLStandardMode, SecureContextMode::kSecureContext,
-      CSSParserContext::kLiveProfile, doc);
-  StyleSheetContents* sheet = StyleSheetContents::Create(context);
-
-  CSSTokenizer tokenizer(":not(*)");
-  const auto tokens = tokenizer.TokenizeToEOF();
-  CSSParserTokenRange range(tokens);
-  CSSSelectorParser::ParseSelector(range, context, sheet);
-
-  EXPECT_FALSE(
-      UseCounter::IsCounted(*doc, WebFeature::kCSSSelectorNotWithValidList));
-  EXPECT_FALSE(
-      UseCounter::IsCounted(*doc, WebFeature::kCSSSelectorNotWithInvalidList));
-  EXPECT_FALSE(UseCounter::IsCounted(
-      *doc, WebFeature::kCSSSelectorNotWithPartiallyValidList));
-}
-
 }  // namespace blink

tools/metrics/histograms/enums.xml

@@ -21527,9 +21527,9 @@ Called by update_net_error_codes.py.-->
   <int value="2642" label="FlexboxSingleLineAlignContent"/>
   <int value="2643" label="SignedExchangeInnerResponseInMainFrame"/>
   <int value="2644" label="SignedExchangeInnerResponseInSubFrame"/>
-  <int value="2645" label="CSSSelectorNotWithValidList"/>
-  <int value="2646" label="CSSSelectorNotWithInvalidList"/>
-  <int value="2647" label="CSSSelectorNotWithPartiallyValidList"/>
+  <int value="2645" label="OBSOLETE_CSSSelectorNotWithValidList"/>
+  <int value="2646" label="OBSOLETE_CSSSelectorNotWithInvalidList"/>
+  <int value="2647" label="OBSOLETE_CSSSelectorNotWithPartiallyValidList"/>
   <int value="2648" label="V8IDBFactory_Databases_Method"/>
   <int value="2649" label="OpenerNavigationDownloadCrossOrigin"/>
   <int value="2650" label="V8RegExpMatchIsTrueishOnNonJSRegExp"/>