TextControl NG: Make LayoutTextControl::GetAvgCharWidth() static and public

This CL will help to implement intrinsic sizes of LayoutNGTextControl*.

- Change the argument of the function to |const ComputedStyle&| in order
to avoid using StyleRef() member function.

This CL has no behavior changes.

Bug: 1040826
Change-Id: Ic66b5a25d28806bfc71ab0011357571924d1e189
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2440725
Commit-Queue: Kent Tamura <tkent@chromium.org>
Commit-Queue: Koji Ishii <kojii@chromium.org>
Auto-Submit: Kent Tamura <tkent@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812617}

third_party/blink/renderer/core/layout/layout_text_control.cc

@@ -208,10 +208,10 @@ bool LayoutTextControl::HasValidAvgCharWidth(const SimpleFontData* font_data,
   return !font_families_with_invalid_char_width_map->Contains(family);
 }
 
-float LayoutTextControl::GetAvgCharWidth(const AtomicString& family) const {
-  NOT_DESTROYED();
-  const Font& font = StyleRef().GetFont();
-
+// static
+float LayoutTextControl::GetAvgCharWidth(const ComputedStyle& style) {
+  const Font& font = style.GetFont();
+  const AtomicString family = font.GetFontDescription().Family().Family();
   const SimpleFontData* primary_font = font.PrimaryFont();
   if (primary_font && HasValidAvgCharWidth(primary_font, family))
     return roundf(primary_font->AvgCharWidth());
@@ -219,7 +219,7 @@ float LayoutTextControl::GetAvgCharWidth(const AtomicString& family) const {
   const UChar kCh = '0';
   const String str = String(&kCh, 1);
   TextRun text_run =
-      ConstructTextRun(font, str, StyleRef(), TextRun::kAllowTrailingExpansion);
+      ConstructTextRun(font, str, style, TextRun::kAllowTrailingExpansion);
   return font.Width(text_run);
 }
 
@@ -229,10 +229,7 @@ MinMaxSizes LayoutTextControl::ComputeIntrinsicLogicalWidths() const {
   sizes += BorderAndPaddingLogicalWidth();
 
   // Use average character width. Matches IE.
-  AtomicString family =
-      StyleRef().GetFont().GetFontDescription().Family().Family();
-  sizes.max_size += PreferredContentLogicalWidth(
-      const_cast<LayoutTextControl*>(this)->GetAvgCharWidth(family));
+  sizes.max_size += PreferredContentLogicalWidth(GetAvgCharWidth(StyleRef()));
   if (InnerEditorElement()) {
     if (LayoutBox* inner_editor_layout_box =
             InnerEditorElement()->GetLayoutBox()) {

third_party/blink/renderer/core/layout/layout_text_control.h

@@ -49,6 +49,8 @@ class CORE_EXPORT LayoutTextControl : public LayoutBlockFlow {
     return true;
   }
 
+  static float GetAvgCharWidth(const ComputedStyle& style);
+
  protected:
   LayoutTextControl(TextControlElement*);
 
@@ -66,7 +68,6 @@ class CORE_EXPORT LayoutTextControl : public LayoutBlockFlow {
 
   static bool HasValidAvgCharWidth(const SimpleFontData*,
                                    const AtomicString& family);
-  float GetAvgCharWidth(const AtomicString& family) const;
   virtual LayoutUnit PreferredContentLogicalWidth(float char_width) const = 0;
   virtual LayoutUnit ComputeControlLogicalHeight(
       LayoutUnit line_height,