Reland 2: mac: Use a placeholder string for the family name of the system font.

Source/core/layout/LayoutTextControlMultiLine.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,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  *
  */
 
 #include "config.h"
 #include "core/layout/LayoutTextControlMultiLine.h"
 
 #include "core/html/HTMLTextAreaElement.h"
 #include "core/layout/HitTestResult.h"
 
+#if defined(WTF_OS_MACOSX)
+#include "platform/mac/VersionUtilMac.h"
+#endif // defined(WTF_OS_MACOSX)
+
 namespace blink {
 
 LayoutTextControlMultiLine::LayoutTextControlMultiLine(HTMLTextAreaElement* element)
     : LayoutTextControl(element)
 {
     ASSERT(element);
 }
 
 LayoutTextControlMultiLine::~LayoutTextControlMultiLine()
 {
 }
 
 bool LayoutTextControlMultiLine::nodeAtPoint(HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction hitTestAction)
 {
     if (!LayoutTextControl::nodeAtPoint(result, locationInContainer, accumulatedOffset, hitTestAction))
         return false;
 
     if (result.innerNode() == node() || result.innerNode() == innerEditorElement())
         hitInnerEditorElement(result, locationInContainer.point(), accumulatedOffset);
 
     return true;
 }
 
 float LayoutTextControlMultiLine::getAvgCharWidth(const AtomicString& family) const
 {
-    // Since Lucida Grande is the default font, we want this to match the width
-    // of Courier New, the default font for textareas in IE, Firefox and Safari Win.
-    // 1229 is the avgCharWidth value in the OS/2 table for Courier New.
-    if (family == "Lucida Grande")
+// Match the default system font to the width of MS Shell Dlg, the default
+// font for textareas in Firefox, Safari Win and IE for some encodings (in
+// IE, the default font is encoding specific). 1229 is the avgCharWidth
+// value in the OS/2 table for Courier New.
+// This is a hack which Blink no longer applies on OSX 10.10+.
+// https://code.google.com/p/chromium/issues/detail?id=515989#c8
+#if defined(WTF_OS_MACOSX)

[tkent, 2015/08/11 01:34:36]

We'd like to minimize OS-specific code in core/.  Please add new function to
LayoutTheme like LayoutTheme::needsSystemFontHackForTextControl(), implement it
in LayoutThemeMac.

[erikchen, 2015/08/11 05:21:13]

Done. I made a method called needsHackForTextControlWithFontFamily() which also
does the string comparison.

+    if (family == "BlinkMacSystemFont" && IsOSMavericksOrEarlier())
         return scaleEmToUnits(1229);
+#endif // defined(WTF_OS_MACOSX)
 
     return LayoutTextControl::getAvgCharWidth(family);
 }
 
 LayoutUnit LayoutTextControlMultiLine::preferredContentLogicalWidth(float charWidth) const
 {
     int factor = toHTMLTextAreaElement(node())->cols();
     return static_cast<LayoutUnit>(ceilf(charWidth * factor)) + scrollbarThickness();
 }
 
@@ skipping 27 matching lines @@
         return placeholderLayoutObject;
     LayoutBox* placeholderBox = toLayoutBox(placeholderLayoutObject);
     placeholderBox->mutableStyleRef().setLogicalWidth(Length(contentLogicalWidth() - placeholderBox->borderAndPaddingLogicalWidth(), Fixed));
     placeholderBox->layoutIfNeeded();
     placeholderBox->setX(borderLeft() + paddingLeft());
     placeholderBox->setY(borderTop() + paddingTop());
     return placeholderLayoutObject;
 }
 
 }