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

Source/core/layout/LayoutTextControlSingleLine.cpp

 /**
  * Copyright (C) 2006, 2007, 2010 Apple Inc. All rights reserved.
  *           (C) 2008 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (C) 2010 Google Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
  *
  * 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.
@@ skipping 281 matching lines @@
     ASSERT(hasControlClip());
     LayoutRect clipRect = contentBoxRect();
     if (containerElement()->layoutBox())
         clipRect = unionRect(clipRect, containerElement()->layoutBox()->frameRect());
     clipRect.moveBy(additionalOffset);
     return clipRect;
 }
 
 float LayoutTextControlSingleLine::getAvgCharWidth(const AtomicString& family) const
 {
-    // Since Lucida Grande is the default font, we want this to match 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).
-    // 901 is the avgCharWidth value in the OS/2 table for MS Shell Dlg.
-    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). 901 is the avgCharWidth value
+    // in the OS/2 table for MS Shell Dlg.
+    // This is a hack which Blink no longer applies on OSX 10.10+.

[tkent, 2015/08/11 05:24:48]

nit: This line looks redundant because LayoutThemeMac.mm has it.

[erikchen, 2015/08/11 05:30:02]

Done.

+    // https://code.google.com/p/chromium/issues/detail?id=515989#c8
+    if (LayoutTheme::theme().needsHackForTextControlWithFontFamily(family))
         return scaleEmToUnits(901);
 
     return LayoutTextControl::getAvgCharWidth(family);
 }
 
 LayoutUnit LayoutTextControlSingleLine::preferredContentLogicalWidth(float charWidth) const
 {
     int factor;
     bool includesDecoration = inputElement()->sizeShouldIncludeDecoration(factor);
     if (factor <= 0)
         factor = 20;
 
     LayoutUnit result = LayoutUnit::fromFloatCeil(charWidth * factor);
 
     float maxCharWidth = 0.f;
     AtomicString family = styleRef().font().fontDescription().family().family();
-    // Since Lucida Grande is the default font, we want this to match 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).
-    // 4027 is the (xMax - xMin) value in the "head" font table for MS Shell Dlg.
-    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). 4027 is the (xMax - xMin)
+    // value in the "head" font table for MS Shell Dlg.
+    // This is a hack which Blink no longer applies on OSX 10.10+.

[tkent, 2015/08/11 05:24:48]

Ditto.

[erikchen, 2015/08/11 05:30:02]

Done.

+    // https://code.google.com/p/chromium/issues/detail?id=515989#c8
+    if (LayoutTheme::theme().needsHackForTextControlWithFontFamily(family))
         maxCharWidth = scaleEmToUnits(4027);
     else if (hasValidAvgCharWidth(family))
         maxCharWidth = roundf(styleRef().font().primaryFont()->maxCharWidth());
 
     // For text inputs, IE adds some extra width.
     if (maxCharWidth > 0.f)
         result += maxCharWidth - charWidth;
 
     if (includesDecoration) {
         HTMLElement* spinButton = innerSpinButtonElement();
@@ skipping 107 matching lines @@
     if (innerEditorElement())
         innerEditorElement()->setScrollTop(newTop);
 }
 
 HTMLInputElement* LayoutTextControlSingleLine::inputElement() const
 {
     return toHTMLInputElement(node());
 }
 
 }