Simplify LayoutSVGText structural invalidation

Currently there are three different methods - SubtreeChildWasAdded,
SubtreeChildWillBeRemoved and SubtreeTextDidChange - that are almost
identical. Most callsites call them by first getting a LayoutSVGText
from LocateLayoutSVGTextAncestor and then calling the method if an
appropriate ancestor is found.

Instead add a static LayoutSVGText::NotifySubtreeStructureChanged which
find an ancestor and calls a new merged version of the above methods,
SubtreeStructureChanged. Also fold InvalidatePositioningValues() into
the new method since it is it's only caller.

Change-Id: I797d350acf76f6a3372d0833566313d304d16fd2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2087400Reviewed-by: Stephen Chenney <schenney@chromium.org>
Commit-Queue: Fredrik Söderquist <fs@opera.com>
Cr-Commit-Position: refs/heads/master@{#746792}

third_party/blink/renderer/core/layout/svg/layout_svg_inline.cc

@@ -146,18 +146,14 @@ void LayoutSVGInline::AddChild(LayoutObject* child,
                                LayoutObject* before_child) {
   LayoutInline::AddChild(child, before_child);
   SVGResourcesCache::ClientWasAddedToTree(*child);
-
-  if (LayoutSVGText* text_layout_object =
-          LayoutSVGText::LocateLayoutSVGTextAncestor(this))
-    text_layout_object->SubtreeChildWasAdded();
+  LayoutSVGText::NotifySubtreeStructureChanged(
+      this, layout_invalidation_reason::kChildChanged);
 }
 
 void LayoutSVGInline::RemoveChild(LayoutObject* child) {
   SVGResourcesCache::ClientWillBeRemovedFromTree(*child);
-
-  if (LayoutSVGText* text_layout_object =
-          LayoutSVGText::LocateLayoutSVGTextAncestor(this))
-    text_layout_object->SubtreeChildWillBeRemoved();
+  LayoutSVGText::NotifySubtreeStructureChanged(
+      this, layout_invalidation_reason::kChildChanged);
   LayoutInline::RemoveChild(child);
 }
 

third_party/blink/renderer/core/layout/svg/layout_svg_inline_text.cc

@@ -59,9 +59,8 @@ LayoutSVGInlineText::LayoutSVGInlineText(Node* n,
 void LayoutSVGInlineText::TextDidChange() {
   SetTextInternal(NormalizeWhitespace(GetText().Impl()));
   LayoutText::TextDidChange();
-  if (LayoutSVGText* text_layout_object =
-          LayoutSVGText::LocateLayoutSVGTextAncestor(this))
-    text_layout_object->SubtreeTextDidChange();
+  LayoutSVGText::NotifySubtreeStructureChanged(
+      this, layout_invalidation_reason::kTextChanged);
 }
 
 void LayoutSVGInlineText::StyleDidChange(StyleDifference diff,

third_party/blink/renderer/core/layout/svg/layout_svg_text.cc

@@ -111,15 +111,8 @@ static inline void CollectDescendantTextNodes(
   }
 }
 
-void LayoutSVGText::InvalidatePositioningValues(
+void LayoutSVGText::SubtreeStructureChanged(
     LayoutInvalidationReasonForTracing reason) {
-  descendant_text_nodes_.clear();
-  SetNeedsPositioningValuesUpdate();
-  // TODO(fs): Restore the passing of |reason| here.
-  LayoutSVGResourceContainer::MarkForLayoutAndParentResourceInvalidation(*this);
-}
-
-void LayoutSVGText::SubtreeChildWasAdded() {
   if (BeingDestroyed() || !EverHadLayout()) {
     DCHECK(descendant_text_nodes_.IsEmpty());
     return;
@@ -128,37 +121,20 @@ void LayoutSVGText::SubtreeChildWasAdded() {
     return;
 
   // The positioning elements cache depends on the size of each text
-  // layoutObject in the subtree. If this changes, clear the cache. It will be
+  // LayoutObject in the subtree. If this changes, clear the cache. It will be
   // rebuilt on the next layout.
-  InvalidatePositioningValues(layout_invalidation_reason::kChildChanged);
-  SetNeedsTextMetricsUpdate();
-}
-
-void LayoutSVGText::SubtreeChildWillBeRemoved() {
-  if (BeingDestroyed() || !EverHadLayout()) {
-    DCHECK(descendant_text_nodes_.IsEmpty());
-    return;
-  }
-
-  // The positioning elements cache depends on the size of each text
-  // layoutObject in the subtree. If this changes, clear the cache. It will be
-  // rebuilt on the next layout.
-  InvalidatePositioningValues(layout_invalidation_reason::kChildChanged);
+  descendant_text_nodes_.clear();
+  SetNeedsPositioningValuesUpdate();
   SetNeedsTextMetricsUpdate();
+  // TODO(fs): Restore the passing of |reason| here.
+  LayoutSVGResourceContainer::MarkForLayoutAndParentResourceInvalidation(*this);
 }
 
-void LayoutSVGText::SubtreeTextDidChange() {
-  DCHECK(!BeingDestroyed());
-  if (!EverHadLayout()) {
-    DCHECK(descendant_text_nodes_.IsEmpty());
-    return;
-  }
-
-  // The positioning elements cache depends on the size of each text object in
-  // the subtree. If this changes, clear the cache and mark it for rebuilding
-  // in the next layout.
-  InvalidatePositioningValues(layout_invalidation_reason::kTextChanged);
-  SetNeedsTextMetricsUpdate();
+void LayoutSVGText::NotifySubtreeStructureChanged(
+    LayoutObject* object,
+    LayoutInvalidationReasonForTracing reason) {
+  if (LayoutSVGText* layout_text = LocateLayoutSVGTextAncestor(object))
+    layout_text->SubtreeStructureChanged(reason);
 }
 
 static inline void UpdateFontAndMetrics(LayoutSVGText& text_root) {
@@ -429,12 +405,12 @@ void LayoutSVGText::AddChild(LayoutObject* child, LayoutObject* before_child) {
   LayoutSVGBlock::AddChild(child, before_child);
 
   SVGResourcesCache::ClientWasAddedToTree(*child);
-  SubtreeChildWasAdded();
+  SubtreeStructureChanged(layout_invalidation_reason::kChildChanged);
 }
 
 void LayoutSVGText::RemoveChild(LayoutObject* child) {
   SVGResourcesCache::ClientWillBeRemovedFromTree(*child);
-  SubtreeChildWillBeRemoved();
+  SubtreeStructureChanged(layout_invalidation_reason::kChildChanged);
 
   LayoutSVGBlock::RemoveChild(child);
 }

third_party/blink/renderer/core/layout/svg/layout_svg_text.h

@@ -53,15 +53,14 @@ class LayoutSVGText final : public LayoutSVGBlock {
   static LayoutSVGText* LocateLayoutSVGTextAncestor(LayoutObject*);
   static const LayoutSVGText* LocateLayoutSVGTextAncestor(const LayoutObject*);
 
+  static void NotifySubtreeStructureChanged(LayoutObject*,
+                                            LayoutInvalidationReasonForTracing);
+
   bool NeedsReordering() const { return needs_reordering_; }
   const Vector<LayoutSVGInlineText*>& DescendantTextNodes() const {
     return descendant_text_nodes_;
   }
 
-  void SubtreeChildWasAdded();
-  void SubtreeChildWillBeRemoved();
-  void SubtreeTextDidChange();
-
   void RecalcVisualOverflow() override;
 
   const char* GetName() const override { return "LayoutSVGText"; }
@@ -94,7 +93,7 @@ class LayoutSVGText final : public LayoutSVGBlock {
 
   RootInlineBox* CreateRootInlineBox() override;
 
-  void InvalidatePositioningValues(LayoutInvalidationReasonForTracing);
+  void SubtreeStructureChanged(LayoutInvalidationReasonForTracing);
 
   bool needs_reordering_ : 1;
   bool needs_positioning_values_update_ : 1;