Cleanup LayoutTextControl and its subclasses.

Source/core/layout/LayoutTextControl.cpp

 /**
  * Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  *           (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 185 matching lines @@
     "#HeadLineA",
     "#PCMyungjo",
     "#PilGi",
 };
 
 // For font families where any of the fonts don't have a valid entry in the OS/2 table
 // for avgCharWidth, fallback to the legacy webkit behavior of getting the avgCharWidth
 // from the width of a '0'. This only seems to apply to a fixed number of Mac fonts,
 // but, in order to get similar rendering across platforms, we do this check for
 // all platforms.
-bool LayoutTextControl::hasValidAvgCharWidth(AtomicString family)
+bool LayoutTextControl::hasValidAvgCharWidth(const AtomicString& family)
 {
     static HashSet<AtomicString>* fontFamiliesWithInvalidCharWidthMap = nullptr;
 
     if (family.isEmpty())
         return false;
 
     if (!fontFamiliesWithInvalidCharWidthMap) {
         fontFamiliesWithInvalidCharWidthMap = new HashSet<AtomicString>;
 
         for (size_t i = 0; i < WTF_ARRAY_LENGTH(fontFamiliesWithInvalidCharWidth); ++i)
             fontFamiliesWithInvalidCharWidthMap->add(AtomicString(fontFamiliesWithInvalidCharWidth[i]));
     }
 
     return !fontFamiliesWithInvalidCharWidthMap->contains(family);
 }
 
-float LayoutTextControl::getAvgCharWidth(AtomicString family)
+float LayoutTextControl::getAvgCharWidth(const AtomicString& family) const
 {
     if (hasValidAvgCharWidth(family))
         return roundf(style()->font().primaryFont()->avgCharWidth());
 
     const UChar ch = '0';
     const String str = String(&ch, 1);
     const Font& font = style()->font();
     TextRun textRun = constructTextRun(font, str, styleRef(), TextRun::AllowTrailingExpansion);
     return font.width(textRun);
 }
@@ skipping 58 matching lines @@
     HTMLElement* placeholder = toHTMLTextFormControlElement(node())->placeholderElement();
     LayoutObject* placeholderLayoutObject = placeholder ? placeholder->layoutObject() : nullptr;
     if (!placeholderLayoutObject)
         return nullptr;
     if (relayoutChildren)
         layoutScope.setChildNeedsLayout(placeholderLayoutObject);
     return placeholderLayoutObject;
 }
 
 } // namespace blink