Add WebVTT support for inline styling - style resolution components

Bug: 724598
Change-Id: If27937335d5761a227e62218fe47cdf30bf20c3a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1863357
Commit-Queue: Evan Liu <evliu@google.com>
Reviewed-by: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#706990}

third_party/blink/renderer/core/css/element_rule_collector.cc

@@ -133,6 +133,7 @@ void ElementRuleCollector::CollectMatchingRulesForList(
       &context_.GetElement(), SelectorChecker::kVisitedMatchEnabled);
   context.scope = match_request.scope;
   context.pseudo_id = pseudo_style_request_.pseudo_id;
+  context.is_from_vtt = match_request.is_from_vtt;
 
   unsigned rejected = 0;
   unsigned fast_rejected = 0;

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

@@ -73,7 +73,8 @@ CSSValueList* ConsumeFontFaceUnicodeRange(CSSParserTokenRange& range) {
 CSSValue* ConsumeFontFaceSrcURI(CSSParserTokenRange& range,
                                 const CSSParserContext& context) {
   String url =
-      css_property_parser_helpers::ConsumeUrlAsStringView(range).ToString();
+      css_property_parser_helpers::ConsumeUrlAsStringView(range, &context)
+          .ToString();
   if (url.IsNull())
     return nullptr;
   CSSFontFaceSrcValue* uri_value(CSSFontFaceSrcValue::Create(

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

@@ -668,13 +668,14 @@ CSSStringValue* ConsumeString(CSSParserTokenRange& range) {
       range.ConsumeIncludingWhitespace().Value().ToString());
 }
 
-StringView ConsumeUrlAsStringView(CSSParserTokenRange& range) {
+StringView ConsumeUrlAsStringView(CSSParserTokenRange& range,
+                                  const CSSParserContext* context) {
+  StringView url;
   const CSSParserToken& token = range.Peek();
   if (token.GetType() == kUrlToken) {
     range.ConsumeIncludingWhitespace();
-    return token.Value();
-  }
-  if (token.FunctionId() == CSSValueID::kUrl) {
+    url = token.Value();
+  } else if (token.FunctionId() == CSSValueID::kUrl) {
     CSSParserTokenRange url_range = range;
     CSSParserTokenRange url_args = url_range.ConsumeBlock();
     const CSSParserToken& next = url_args.ConsumeIncludingWhitespace();
@@ -683,15 +684,27 @@ StringView ConsumeUrlAsStringView(CSSParserTokenRange& range) {
     DCHECK_EQ(next.GetType(), kStringToken);
     range = url_range;
     range.ConsumeWhitespace();
-    return next.Value();
+    url = next.Value();
+  }
+
+  // Invalidate the URL if only data URLs are allowed and the protocol is not
+  // data.
+  if (!url.IsNull() &&
+      context->ResourceFetchRestriction() ==
+          ResourceFetchRestriction::kOnlyDataUrls &&
+      !ProtocolIs(url.ToString(), "data")) {
+    // The StringView must be instantiated with an empty string otherwise the
+    // URL will incorrectly be identified as null. The resource should behave as
+    // if it failed to load.
+    url = StringView("");
   }
 
-  return StringView();
+  return url;
 }
 
 CSSURIValue* ConsumeUrl(CSSParserTokenRange& range,
                         const CSSParserContext* context) {
-  StringView url = ConsumeUrlAsStringView(range);
+  StringView url = ConsumeUrlAsStringView(range, context);
   if (url.IsNull())
     return nullptr;
   String url_string = url.ToString();
@@ -1758,7 +1771,8 @@ static CSSValue* ConsumeImageSet(CSSParserTokenRange& range,
   CSSParserTokenRange args = ConsumeFunction(range_copy);
   auto* image_set = MakeGarbageCollected<CSSImageSetValue>(context->Mode());
   do {
-    AtomicString url_value = ConsumeUrlAsStringView(args).ToAtomicString();
+    AtomicString url_value =
+        ConsumeUrlAsStringView(args, context).ToAtomicString();
     if (url_value.IsNull())
       return nullptr;
 
@@ -1801,7 +1815,7 @@ static bool IsGeneratedImage(CSSValueID id) {
 CSSValue* ConsumeImage(CSSParserTokenRange& range,
                        const CSSParserContext* context,
                        ConsumeGeneratedImagePolicy generated_image) {
-  AtomicString uri = ConsumeUrlAsStringView(range).ToAtomicString();
+  AtomicString uri = ConsumeUrlAsStringView(range, context).ToAtomicString();
   if (!uri.IsNull())
     return CreateCSSImageValueWithReferrer(uri, context);
   if (range.Peek().GetType() == kFunctionToken) {

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

@@ -94,7 +94,8 @@ CSSIdentifierValue* ConsumeIdent(CSSParserTokenRange&);
 CSSCustomIdentValue* ConsumeCustomIdent(CSSParserTokenRange&,
                                         const CSSParserContext&);
 CSSStringValue* ConsumeString(CSSParserTokenRange&);
-StringView ConsumeUrlAsStringView(CSSParserTokenRange&);
+StringView ConsumeUrlAsStringView(CSSParserTokenRange&,
+                                  const CSSParserContext*);
 cssvalue::CSSURIValue* ConsumeUrl(CSSParserTokenRange&,
                                   const CSSParserContext*);
 

third_party/blink/renderer/core/css/resolver/match_request.h

@@ -41,11 +41,13 @@ class MatchRequest {
   MatchRequest(RuleSet* rule_set,
                const ContainerNode* scope = nullptr,
                const CSSStyleSheet* css_sheet = nullptr,
-               unsigned style_sheet_index = 0)
+               unsigned style_sheet_index = 0,
+               bool is_from_vtt = false)
       : rule_set(rule_set),
         scope(scope),
         style_sheet(css_sheet),
-        style_sheet_index(style_sheet_index) {
+        style_sheet_index(style_sheet_index),
+        is_from_vtt(is_from_vtt) {
     // Now that we're about to read from the RuleSet, we're done adding more
     // rules to the set and we should make sure it's compacted.
     rule_set->CompactRulesIfNeeded();
@@ -55,6 +57,7 @@ class MatchRequest {
   Member<const ContainerNode> scope;
   Member<const CSSStyleSheet> style_sheet;
   const unsigned style_sheet_index;
+  bool is_from_vtt;
 };
 
 }  // namespace blink

third_party/blink/renderer/core/css/resolver/style_resolver.cc

@@ -58,7 +58,6 @@
 #include "third_party/blink/renderer/core/css/css_value_list.h"
 #include "third_party/blink/renderer/core/css/element_rule_collector.h"
 #include "third_party/blink/renderer/core/css/font_face.h"
-#include "third_party/blink/renderer/core/css/media_query_evaluator.h"
 #include "third_party/blink/renderer/core/css/page_rule_collector.h"
 #include "third_party/blink/renderer/core/css/part_names.h"
 #include "third_party/blink/renderer/core/css/properties/css_property.h"
@@ -66,7 +65,6 @@
 #include "third_party/blink/renderer/core/css/resolver/css_variable_animator.h"
 #include "third_party/blink/renderer/core/css/resolver/css_variable_resolver.h"
 #include "third_party/blink/renderer/core/css/resolver/match_result.h"
-#include "third_party/blink/renderer/core/css/resolver/media_query_result.h"
 #include "third_party/blink/renderer/core/css/resolver/scoped_style_resolver.h"
 #include "third_party/blink/renderer/core/css/resolver/selector_filter_parent_scope.h"
 #include "third_party/blink/renderer/core/css/resolver/style_adjuster.h"
@@ -90,6 +88,9 @@
 #include "third_party/blink/renderer/core/html/custom/custom_element_definition.h"
 #include "third_party/blink/renderer/core/html/html_iframe_element.h"
 #include "third_party/blink/renderer/core/html/html_slot_element.h"
+#include "third_party/blink/renderer/core/html/track/text_track.h"
+#include "third_party/blink/renderer/core/html/track/vtt/vtt_cue.h"
+#include "third_party/blink/renderer/core/html/track/vtt/vtt_element.h"
 #include "third_party/blink/renderer/core/html_names.h"
 #include "third_party/blink/renderer/core/media_type_names.h"
 #include "third_party/blink/renderer/core/probe/core_probes.h"
@@ -312,6 +313,38 @@ static void MatchSlottedRules(const Element& element,
   }
 }
 
+const static TextTrack* GetTextTrackFromElement(const Element& element) {
+  if (auto* vtt_element = DynamicTo<VTTElement>(element))
+    return vtt_element->GetTrack();
+  if (auto* vtt_cue_background_box = DynamicTo<VTTCueBackgroundBox>(element))
+    return vtt_cue_background_box->GetTrack();
+  return nullptr;
+}
+
+static void MatchVTTRules(const Element& element,
+                                  ElementRuleCollector& collector) {
+  const TextTrack* text_track = GetTextTrackFromElement(element);
+  if (!text_track)
+    return;
+  const HeapVector<Member<CSSStyleSheet>>& styles =
+      text_track->GetCSSStyleSheets();
+  if (!styles.IsEmpty()) {
+    int style_sheet_index = 0;
+    collector.ClearMatchedRules();
+    for (CSSStyleSheet* style : styles) {
+      RuleSet* rule_set =
+          element.GetDocument().GetStyleEngine().RuleSetForSheet(*style);
+      if (rule_set) {
+        collector.CollectMatchingRules(
+            MatchRequest(rule_set, nullptr /* scope */, style,
+                         style_sheet_index, true /* is_from_webvtt */));
+        style_sheet_index++;
+      }
+    }
+    collector.SortAndTransferMatchedRules();
+  }
+}
+
 // Matches rules from the element's scope. The selectors may cross shadow
 // boundaries during matching, like for :host-context.
 static void MatchElementScopeRules(const Element& element,
@@ -324,6 +357,7 @@ static void MatchElementScopeRules(const Element& element,
     collector.SortAndTransferMatchedRules();
   }
 
+  MatchVTTRules(element, collector);
   if (element.IsStyledElement() && element.InlineStyle() &&
       !collector.IsCollectingForPseudoElement()) {
     // Inline style is immutable as long as there is no CSSOM wrapper.

third_party/blink/renderer/core/css/selector_checker.cc

@@ -88,8 +88,10 @@ static bool MatchesListBoxPseudoClass(const Element& element) {
   return html_select_element && !html_select_element->UsesMenuList();
 }
 
-static bool MatchesTagName(const Element& element,
-                           const QualifiedName& tag_q_name) {
+static bool MatchesTagName(
+    const Element& element,
+    const QualifiedName& tag_q_name,
+    const SelectorChecker::SelectorCheckingContext& context) {
   if (tag_q_name == AnyQName())
     return true;
   const AtomicString& local_name = tag_q_name.LocalName();
@@ -105,8 +107,12 @@ static bool MatchesTagName(const Element& element,
       return false;
   }
   const AtomicString& namespace_uri = tag_q_name.NamespaceURI();
-  return namespace_uri == g_star_atom ||
-         namespace_uri == element.namespaceURI();
+  if (namespace_uri == g_star_atom)
+    return true;
+  // VTT style sheets should apply to a hypothetical document with no namespace
+  if (context.is_from_vtt)
+    return namespace_uri.IsEmpty();
+  return namespace_uri == element.namespaceURI();
 }
 
 static Element* ParentElement(
@@ -204,6 +210,26 @@ static bool IsLastOfType(Element& element, const QualifiedName& type) {
   return !ElementTraversal::NextSibling(element, HasTagName(type));
 }
 
+bool SelectorChecker::Match(const SelectorCheckingContext& context,
+                            MatchResult& result) const {
+  DCHECK(context.selector);
+  if (context.is_from_vtt)
+    return MatchVTTBlockSelector(context, result);
+  return MatchSelector(context, result) == kSelectorMatches;
+}
+
+bool SelectorChecker::MatchVTTBlockSelector(
+    const SelectorCheckingContext& context,
+    MatchResult& result) const {
+  DCHECK(context.selector);
+  if (context.selector->IsLastInTagHistory() ||
+      context.selector->TagHistory()->Specificity() != 0) {
+    return false;
+  }
+
+  return MatchSelector(context, result) == kSelectorMatches;
+}
+
 // Recursive check of selectors and combinators
 // It can return 4 different values:
 // * SelectorMatches          - the selector matches the element e
@@ -330,6 +356,14 @@ SelectorChecker::MatchStatus SelectorChecker::MatchForRelation(
   next_context.previous_element = context.element;
   next_context.pseudo_id = kPseudoIdNone;
 
+  // Rules that come from a WebVTT STYLE block apply to a hypothetical
+  // document with a single empty element with no explicit name, no namespace,
+  // no attribute, no classes, no IDs, and unknown primary language that acts
+  // as the originating element for the cue pseudo-elements. This element
+  // must not be generally selectable.
+  if (context.is_from_vtt && relation != CSSSelector::kShadowPseudo)
+    return kSelectorFailsCompletely;
+
   switch (relation) {
     case CSSSelector::kShadowDeepAsDescendant:
       Deprecation::CountDeprecation(context.element->GetDocument(),
@@ -690,7 +724,7 @@ bool SelectorChecker::CheckOne(const SelectorCheckingContext& context,
 
   switch (selector.Match()) {
     case CSSSelector::kTag:
-      return MatchesTagName(element, selector.TagQName());
+      return MatchesTagName(element, selector.TagQName(), context);
     case CSSSelector::kClass:
       return element.HasClass() &&
              element.ClassNames().Contains(selector.Value());
@@ -896,7 +930,8 @@ bool SelectorChecker::CheckPseudoClass(const SelectorCheckingContext& context,
       for (sub_context.selector = selector.SelectorList()->First();
            sub_context.selector; sub_context.selector = CSSSelectorList::Next(
                                      *sub_context.selector)) {
-        if (Match(sub_context))
+        MatchResult sub_result;
+        if (MatchSelector(sub_context, sub_result) == kSelectorMatches)
           return true;
       }
     } break;
@@ -1150,7 +1185,8 @@ bool SelectorChecker::CheckPseudoElement(const SelectorCheckingContext& context,
       for (sub_context.selector = selector.SelectorList()->First();
            sub_context.selector; sub_context.selector = CSSSelectorList::Next(
                                      *sub_context.selector)) {
-        if (Match(sub_context))
+        MatchResult sub_result;
+        if (MatchSelector(sub_context, sub_result) == kSelectorMatches)
           return true;
       }
       return false;

third_party/blink/renderer/core/css/selector_checker.h

@@ -115,7 +115,8 @@ class SelectorChecker {
           in_rightmost_compound(true),
           has_scrollbar_pseudo(false),
           has_selection_pseudo(false),
-          treat_shadow_host_as_normal_scope(false) {}
+          treat_shadow_host_as_normal_scope(false),
+          is_from_vtt(false) {}
 
     const CSSSelector* selector;
     Member<Element> element;
@@ -128,6 +129,7 @@ class SelectorChecker {
     bool has_scrollbar_pseudo;
     bool has_selection_pseudo;
     bool treat_shadow_host_as_normal_scope;
+    bool is_from_vtt;
   };
 
   struct MatchResult {
@@ -140,11 +142,7 @@ class SelectorChecker {
     unsigned specificity;
   };
 
-  bool Match(const SelectorCheckingContext& context,
-             MatchResult& result) const {
-    DCHECK(context.selector);
-    return MatchSelector(context, result) == kSelectorMatches;
-  }
+  bool Match(const SelectorCheckingContext& context, MatchResult& result) const;
 
   bool Match(const SelectorCheckingContext& context) const {
     MatchResult ignore_result;
@@ -196,6 +194,8 @@ class SelectorChecker {
   MatchStatus MatchForPseudoShadow(const SelectorCheckingContext&,
                                    const ContainerNode*,
                                    MatchResult&) const;
+  bool MatchVTTBlockSelector(const SelectorCheckingContext& context,
+                             MatchResult& result) const;
   bool CheckPseudoClass(const SelectorCheckingContext&, MatchResult&) const;
   bool CheckPseudoElement(const SelectorCheckingContext&, MatchResult&) const;
   bool CheckScrollbarPseudoClass(const SelectorCheckingContext&,