[WIP] WebFonts cache-aware timeout adaption

third_party/WebKit/Source/core/css/CSSFontFaceSrcValue.cpp

Index: third_party/WebKit/Source/core/css/CSSFontFaceSrcValue.cpp
diff --git a/third_party/WebKit/Source/core/css/CSSFontFaceSrcValue.cpp b/third_party/WebKit/Source/core/css/CSSFontFaceSrcValue.cpp
index 6a88cbe223d3a28d1510ec6cb5bf1bc2700cdbaf..fb8e7b5e567bebac0b87ab76c76c47b0d48aa73c 100644
--- a/third_party/WebKit/Source/core/css/CSSFontFaceSrcValue.cpp
+++ b/third_party/WebKit/Source/core/css/CSSFontFaceSrcValue.cpp
@@ -88,6 +88,7 @@ FontResource* CSSFontFaceSrcValue::fetch(Document* document) const {
   if (!m_fetched) {
     FetchRequest request(ResourceRequest(m_absoluteResource),
                          FetchInitiatorTypeNames::css);
+    request.mutableResourceRequest().setIsCacheAwareLoadingEnabled(true);

[Kunihiko Sakamoto, 2016/10/03 08:31:38]

I think we should do cache-aware loading only for @font-faces with font-display:
(swap | fallback | optional).
See the table in Toyoshima-san's doc:
https://docs.google.com/document/d/1SKRVFza_USrdVZgJmPnKWmqbzj-kVoxMB2ECH_xLh...

[Takashi Toyoshima, 2016/10/03 09:01:04]

Since it will introduce additional complexity, we would use cache-aware loading
always for WebFonts. This decision is based on data that requests rarely miss
the cache and disk check is reasonable fast compared to network access in the
case of cache miss.

But, probably we should make this feature behind a flag.

shao, can you add a new Runtime flag in
Source/platform/RuntimeEnabledFeatures.in, and set it only when the runtime flag
is set?
Probably, it should contain status=experimental so that it is enabled in tests
or users who enable chrome://flags/#enable-experimental-web-platform-features

[Shao-Chuan Lee, 2016/10/04 09:08:04]

Done.

     request.setContentSecurityCheck(m_shouldCheckContentSecurityPolicy);
     SecurityOrigin* securityOrigin = document->getSecurityOrigin();
     setCrossOriginAccessControl(request, securityOrigin);