Expand system font values during property parsing.

Source/core/rendering/RenderTheme.cpp

Index: Source/core/rendering/RenderTheme.cpp
diff --git a/Source/core/rendering/RenderTheme.cpp b/Source/core/rendering/RenderTheme.cpp
index b150048a564f303cdd7ad83b48a5835f45ed66cc..f07705b80733f7292781595312792a7370615a39 100644
--- a/Source/core/rendering/RenderTheme.cpp
+++ b/Source/core/rendering/RenderTheme.cpp
@@ -940,6 +940,64 @@ void RenderTheme::platformColorsDidChange()
     Page::scheduleForcedStyleRecalcForAllPages();
 }
 
+static FontDescription& getCachedFontDescription(CSSValueID systemFontID)
+{
+    DEFINE_STATIC_LOCAL(FontDescription, caption, ());
+    DEFINE_STATIC_LOCAL(FontDescription, icon, ());
+    DEFINE_STATIC_LOCAL(FontDescription, menu, ());
+    DEFINE_STATIC_LOCAL(FontDescription, messageBox, ());
+    DEFINE_STATIC_LOCAL(FontDescription, smallCaption, ());
+    DEFINE_STATIC_LOCAL(FontDescription, statusBar, ());
+    DEFINE_STATIC_LOCAL(FontDescription, webkitMiniControl, ());
+    DEFINE_STATIC_LOCAL(FontDescription, webkitSmallControl, ());
+    DEFINE_STATIC_LOCAL(FontDescription, webkitControl, ());
+    DEFINE_STATIC_LOCAL(FontDescription, defaultDescription, ());
+    switch (systemFontID) {
+    case CSSValueCaption:
+        return caption;
+    case CSSValueIcon:
+        return icon;
+    case CSSValueMenu:
+        return menu;
+    case CSSValueMessageBox:
+        return messageBox;
+    case CSSValueSmallCaption:
+        return smallCaption;
+    case CSSValueStatusBar:
+        return statusBar;
+    case CSSValueWebkitMiniControl:
+        return webkitMiniControl;
+    case CSSValueWebkitSmallControl:
+        return webkitSmallControl;
+    case CSSValueWebkitControl:
+        return webkitControl;
+    case CSSValueNone:

[alancutter (OOO until 2018), 2014/10/26 23:40:19]

When would this case be reached?

[Timothy Loh, 2014/10/27 05:45:46]

I think only in DragContoller.cpp/dragImageForLink. Seems a bit dodgy, but
probably OK.

[andersr, 2014/10/27 10:58:30]

Yes, that's the only place. By letting CSSValueNone mean "default system font"
here, that code should work approximately like before.

+        return defaultDescription;
+    default:
+        ASSERT_NOT_REACHED();
+        return defaultDescription;
+    }
+}
+
+void RenderTheme::systemFont(CSSValueID systemFontID, FontDescription& fontDescription)
+{
+    fontDescription = getCachedFontDescription(systemFontID);
+    if (fontDescription.isAbsoluteSize())
+        return;
+
+    FontStyle fontStyle = FontStyleNormal;
+    FontWeight fontWeight = FontWeightNormal;
+    float fontSize = 0;
+    AtomicString fontFamily;
+    systemFont(systemFontID, fontStyle, fontWeight, fontSize, fontFamily);
+    fontDescription.setStyle(fontStyle);
+    fontDescription.setWeight(fontWeight);
+    fontDescription.setSpecifiedSize(fontSize);
+    fontDescription.setIsAbsoluteSize(true);
+    fontDescription.firstFamily().setFamily(fontFamily);
+    fontDescription.setGenericFamily(FontDescription::NoFamily);
+}
+
 Color RenderTheme::systemColor(CSSValueID cssValueId) const
 {
     switch (cssValueId) {