Refactor dirty font cache handling.

ApplyRuleSetChanges was hard to understand because it contained various
branching for user style updates which wasn't clear were for user style.
Move the user style specific font and keyframes handling to a separate
ApplyUserRuleSetChanges and create a common InvalidateForRuleSetChanges
to do the common code for marking nodes for style invalidation/recalc.

Change-Id: I7b4907e526e5768f1957e5be3ad1b41f9a5d35f0
Reviewed-on: https://chromium-review.googlesource.com/c/1258543Reviewed-by: Anders Ruud <andruud@chromium.org>
Commit-Queue: Rune Lillesveen <futhark@chromium.org>
Cr-Commit-Position: refs/heads/master@{#597081}

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

@@ -116,10 +116,13 @@ void FontFaceCache::RemoveFontFace(FontFace* font_face, bool css_connected) {
   IncrementVersion();
 }
 
-void FontFaceCache::ClearCSSConnected() {
+bool FontFaceCache::ClearCSSConnected() {
+  if (style_rule_to_font_face_.IsEmpty())
+    return false;
   for (const auto& item : style_rule_to_font_face_)
     RemoveFontFace(item.value.Get(), true);
   style_rule_to_font_face_.clear();
+  return true;
 }
 
 void FontFaceCache::ClearAll() {

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

@@ -50,7 +50,8 @@ class CORE_EXPORT FontFaceCache final {
 
   void Add(const StyleRuleFontFace*, FontFace*);
   void Remove(const StyleRuleFontFace*);
-  void ClearCSSConnected();
+  // Returns true if at least one font was removed.
+  bool ClearCSSConnected();
   void ClearAll();
   void AddFontFace(FontFace*, bool css_connected);
   void RemoveFontFace(FontFace*, bool css_connected);

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

@@ -318,8 +318,9 @@ class CORE_EXPORT StyleEngine final
 
   void ApplyRuleSetChanges(TreeScope&,
                            const ActiveStyleSheetVector& old_style_sheets,
-                           const ActiveStyleSheetVector& new_style_sheets,
-                           InvalidationScope = kInvalidateCurrentScope);
+                           const ActiveStyleSheetVector& new_style_sheets);
+  void ApplyUserRuleSetChanges(const ActiveStyleSheetVector& old_style_sheets,
+                               const ActiveStyleSheetVector& new_style_sheets);
 
   void CollectMatchingUserRules(ElementRuleCollector&) const;
 
@@ -413,6 +414,11 @@ class CORE_EXPORT StyleEngine final
   void ScheduleTypeRuleSetInvalidations(ContainerNode&,
                                         const HeapHashSet<Member<RuleSet>>&);
   void InvalidateSlottedElements(HTMLSlotElement&);
+  void InvalidateForRuleSetChanges(
+      TreeScope& tree_scope,
+      const HeapHashSet<Member<RuleSet>>& changed_rule_sets,
+      unsigned changed_rule_flags,
+      InvalidationScope invalidation_scope);
 
   void UpdateViewport();
   void UpdateActiveUserStyleSheets();
@@ -425,11 +431,7 @@ class CORE_EXPORT StyleEngine final
   const MediaQueryEvaluator& EnsureMediaQueryEvaluator();
   void UpdateStyleSheetList(TreeScope&);
 
-  void ClearFontCache();
-  void RefreshFontCache();
-  void MarkFontCacheDirty() { font_cache_dirty_ = true; }
-  bool IsFontCacheDirty() const { return font_cache_dirty_; }
-
+  void ClearFontCacheAndAddUserFonts();
   void ClearKeyframeRules() { keyframes_rule_map_.clear(); }
 
   void AddFontFaceRules(const RuleSet&);
@@ -492,7 +494,6 @@ class CORE_EXPORT StyleEngine final
   HeapHashSet<Member<Element>> whitespace_reattach_set_;
 
   Member<CSSFontSelector> font_selector_;
-  bool font_cache_dirty_ = false;
 
   HeapHashMap<AtomicString, WeakMember<StyleSheetContents>>
       text_to_sheet_cache_;