predictors: Support fonts in resource_prefetch_predictors.

chrome/browser/predictors/resource_prefetch_predictor.cc

Index: chrome/browser/predictors/resource_prefetch_predictor.cc
diff --git a/chrome/browser/predictors/resource_prefetch_predictor.cc b/chrome/browser/predictors/resource_prefetch_predictor.cc
index cbabd8d6c1eb69d8a0c373446944e4a88a17dfe9..729ceda1dac6df9df9f7baa5fae04b77f490afe4 100644
--- a/chrome/browser/predictors/resource_prefetch_predictor.cc
+++ b/chrome/browser/predictors/resource_prefetch_predictor.cc
@@ -248,11 +248,10 @@ bool ResourcePrefetchPredictor::IsHandledSubresource(
 
   std::string mime_type;
   response->GetMimeType(&mime_type);
-  if (!mime_type.empty() && !mime_util::IsSupportedImageMimeType(mime_type) &&
-      !mime_util::IsSupportedJavascriptMimeType(mime_type) &&
-      !net::MatchesMimeType("text/css", mime_type)) {
+  const content::ResourceType resource_type =
+      GetResourceTypeFromMimeType(mime_type, content::RESOURCE_TYPE_LAST_TYPE);
+  if (resource_type == content::RESOURCE_TYPE_LAST_TYPE)
     resource_status |= RESOURCE_STATUS_UNSUPPORTED_MIME_TYPE;
-  }
 
   if (response->method() != "GET")
     resource_status |= RESOURCE_STATUS_NOT_GET;
@@ -296,12 +295,16 @@ bool ResourcePrefetchPredictor::IsCacheable(const net::URLRequest* response) {
 content::ResourceType ResourcePrefetchPredictor::GetResourceTypeFromMimeType(
     const std::string& mime_type,
     content::ResourceType fallback) {
-  if (mime_util::IsSupportedImageMimeType(mime_type))
+  if (mime_type.empty())
+    return fallback;
+  else if (mime_util::IsSupportedImageMimeType(mime_type))
     return content::RESOURCE_TYPE_IMAGE;
   else if (mime_util::IsSupportedJavascriptMimeType(mime_type))
     return content::RESOURCE_TYPE_SCRIPT;
   else if (net::MatchesMimeType("text/css", mime_type))
     return content::RESOURCE_TYPE_STYLESHEET;
+  else if (net::MatchesMimeType("application/font-woff", mime_type))

[pasko, 2016/07/28 14:04:04]

let's add more mime types for fonts. I don't know whether all below is properly
recognized, but here is how I found popular font mime types:

cat httparchive_Jul_15_2016_requests.csv | cut -d ',' -f23 | grep font >
/tmp/font-mime-types

$ sort /tmp/font-mime-types | uniq -c | sort -n | grep -v css | tail -30
$ sort /hdd/tmp/font-mime-types | uniq -c | sort -n | grep -v css | tail -30
     11 "font-woff"
     14 "application/font-otf"
     17 "font/font-woff2"
     22 "application/x-font"
     22 "woff/x-font"
     23 "application/font"
     30 "font/x-font-woff"
     41 "x-font/otf"
     42 "font/font-woff"
    190 "x-font/ttf"
    211 "application/x-font-truetype"
    316 "application/x-font-opentype"
    474 "font/x-woff2"
    539 "application/vnd.ms-fontobject"
    567 "font/otf"
    790 "application/x-font-woff2"
    996 "font/truetype"
   1218 "font/opentype"
   1222 "application/font-ttf"
   2092 "application/font-sfnt"
   2172 "x-font/woff"
   2242 "application/x-font-otf"
   7445 "font/ttf"
  12905 "font/woff"
  14095 "application/x-font-ttf"
  14541 "font/x-woff"
  31035 "application/font-woff2"
  86496 "application/font-woff"
 105720 "application/x-font-woff"
 657314 "font/woff2"

.. grepping out 'css' because there are some bugs in my usage of 'cut' and
perhaps also in httparchive.

[Benoit L, 2016/07/28 16:11:53]

Thank you for spotting this!
Done.

+    return content::RESOURCE_TYPE_FONT_RESOURCE;
   else
     return fallback;
 }