Implemented most of HtmlDialogWindowController, which is a Cocoa port

app/gfx/font_mac.mm

Index: app/gfx/font_mac.mm
diff --git a/app/gfx/font_mac.mm b/app/gfx/font_mac.mm
index b39ebea3cf106c2377b60eabc89216d6085c1938..4d0a48ed8bc898466a7042f1023600b455066290 100644
--- a/app/gfx/font_mac.mm
+++ b/app/gfx/font_mac.mm
@@ -33,6 +33,9 @@ Font::Font()
 
 void Font::calculateMetrics() {
   NSFont* font = nativeFont();
+  // TODO(akalin): This is the wrong height to use!  Use either the height
+  // of the bounding rect for the font or ascender - descender; this needs
+  // further investigation.  Width may be wrong, too.
   height_ = [font xHeight];
   ascent_ = [font ascender];
   avg_width_ = [font boundingRectForGlyph:[font glyphWithName:@"x"]].size.width;