DirectWrite doesn't support Bitmap/Vector fonts and Adobe Type 1 fonts.

content/common/dwrite_font_platform_win.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/public/common/dwrite_font_platform_win.h"
 
 #include <dwrite.h>
 #include <map>
 #include <string>
 #include <utility>
@@ skipping 728 matching lines @@
 
 UINT32 FontCollectionLoader::GetFontMapSize() {
   return reg_fonts_.size();
 }
 
 base::string16 FontCollectionLoader::GetFontNameFromKey(UINT32 idx) {
   DCHECK(idx < reg_fonts_.size());
   return reg_fonts_[idx];
 }
 
+const base::FilePath::CharType* kFontExtensionsToIgnore[] {
+  FILE_PATH_LITERAL(".FON"),  // Bitmap or vector

[scottmg, 2015/03/26 01:26:54]

huh! I didn't know .fon had a vector format too.

+  FILE_PATH_LITERAL(".PFM"),  // Adobe Type 1
+  FILE_PATH_LITERAL(".PFB"),  // Adobe Type 1
+};
+
 const wchar_t* kFontsToIgnore[] = {
   // "Gill Sans Ultra Bold" turns into an Ultra Bold weight "Gill Sans" in
   // DirectWrite, but most users don't have any other weights. The regular
   // weight font is named "Gill Sans MT", but that ends up in a different
   // family with that name. On Mac, there's a "Gill Sans" with various weights,
   // so CSS authors use { 'font-family': 'Gill Sans', 'Gill Sans MT', ... } and
   // because of the DirectWrite family futzing, they end up with an Ultra Bold
   // font, when they just wanted "Gill Sans". Mozilla implemented a more
   // complicated hack where they effectively rename the Ultra Bold font to
   // "Gill Sans MT Ultra Bold", but because the Ultra Bold font is so ugly
@@ skipping 32 matching lines @@
            value.size() < kMaxFontFileNameLength - 1) ||
           base::FilePath::CompareEqualIgnoreCase(system_font_path.value(),
                                                  path.DirName().value())) {
         bool should_ignore = false;
         for (const auto& ignore : kFontsToIgnore) {
           if (base::FilePath::CompareEqualIgnoreCase(path.value(), ignore)) {
             should_ignore = true;
             break;
           }
         }
+        // DirectWrite doesn't support bitmap/vector fonts and Adobe type 1
+        // fonts, we will ignore those font extensions.
+        // MSDN article: http://goo.gl/TfCOA
+        if (!should_ignore) {
+          for (const auto& ignore : kFontExtensionsToIgnore) {
+            if (path.MatchesExtension(ignore)) {
+              should_ignore = true;
+              break;
+            }
+          }
+        }
+
         if (!should_ignore)
           reg_fonts_.push_back(value.c_str());
       }
     }
   }
   UMA_HISTOGRAM_COUNTS("DirectWrite.Fonts.Loaded", reg_fonts_.size());
   UMA_HISTOGRAM_COUNTS("DirectWrite.Fonts.Ignored",
                        regkey.GetValueCount() - reg_fonts_.size());
   return true;
 }
@@ skipping 392 matching lines @@
   g_shared_font_cache.Set(mapping);
 
   return true;
 }
 
 bool BuildFontCache(const base::FilePath& file) {
   return BuildFontCacheInternal(file.value().c_str());
 }
 
 }  // namespace content