Calculate glyph overflow when computing overflow outside of layout

third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp

Index: third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp
diff --git a/third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp b/third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp
index c99a80a9d223a434ab7161328f1b80811064bbba..3d1618bf95d8add60049c2bde95db2ad9e02aac6 100644
--- a/third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp
+++ b/third_party/WebKit/Source/core/layout/line/InlineFlowBox.cpp
@@ -1161,6 +1161,41 @@ inline void InlineFlowBox::addReplacedChildOverflow(
   logicalLayoutOverflow.unite(childLogicalLayoutOverflow);
 }
 
+static void computeGlyphOverflow(
+    InlineTextBox* text,
+    const LineLayoutText& layoutText,
+    GlyphOverflowAndFallbackFontsMap& textBoxDataMap) {
+  HashSet<const SimpleFontData*> fallbackFonts;
+  FloatRect glyphBounds;
+  GlyphOverflow glyphOverflow;
+  float measuredWidth =
+      layoutText.width(text->start(), text->len(), LayoutUnit(),
+                       text->direction(), false, &fallbackFonts, &glyphBounds);
+  const Font& font = layoutText.style()->font();
+  const SimpleFontData* fontData = font.primaryFont();
+  DCHECK(fontData);
+  glyphOverflow.setFromBounds(
+      glyphBounds, fontData ? fontData->getFontMetrics().floatAscent() : 0,
+      fontData ? fontData->getFontMetrics().floatDescent() : 0, measuredWidth);
+  if (!fallbackFonts.isEmpty()) {
+    GlyphOverflowAndFallbackFontsMap::ValueType* it =
+        textBoxDataMap
+            .insert(text, std::make_pair(Vector<const SimpleFontData*>(),
+                                         GlyphOverflow()))
+            .storedValue;
+    DCHECK(it->value.first.isEmpty());
+    copyToVector(fallbackFonts, it->value.first);
+  }
+  if (!glyphOverflow.isApproximatelyZero()) {
+    GlyphOverflowAndFallbackFontsMap::ValueType* it =
+        textBoxDataMap
+            .insert(text, std::make_pair(Vector<const SimpleFontData*>(),
+                                         GlyphOverflow()))
+            .storedValue;
+    it->value.second = glyphOverflow;
+  }
+}
+
 void InlineFlowBox::computeOverflow(
     LayoutUnit lineTop,
     LayoutUnit lineBottom,
@@ -1196,7 +1231,15 @@ void InlineFlowBox::computeOverflow(
       if (rt.isBR())
         continue;
       LayoutRect textBoxOverflow(text->logicalFrameRect());
-      addTextBoxVisualOverflow(text, textBoxDataMap, textBoxOverflow);
+      if (textBoxDataMap.isEmpty()) {
+        // An empty glyph map means that we're computing overflow without
+        // a layout, so calculate the glyph overflow on the fly.
+        GlyphOverflowAndFallbackFontsMap glyphOverflowForText;
+        computeGlyphOverflow(text, rt, glyphOverflowForText);
+        addTextBoxVisualOverflow(text, glyphOverflowForText, textBoxOverflow);
+      } else {
+        addTextBoxVisualOverflow(text, textBoxDataMap, textBoxOverflow);
+      }
       logicalVisualOverflow.unite(textBoxOverflow);
     } else if (curr->getLineLayoutItem().isLayoutInline()) {
       InlineFlowBox* flow = toInlineFlowBox(curr);