Set WebFont priority to very low if the network is detected to be slow

third_party/WebKit/Source/core/fetch/FontResource.h

 /*
  * Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 49 matching lines @@
   bool isCORSFailed() const { return m_corsFailed; }
   String otsParsingMessage() const { return m_otsParsingMessage; }
 
   bool ensureCustomFontData();
   FontPlatformData platformDataFromCustomData(
       float size,
       bool bold,
       bool italic,
       FontOrientation = FontOrientation::Horizontal);
 
+  // Returns true if the loading priority of the remote font resource can be
+  // lowered. The loading priority of the font can be lowered only if the
+  // font is not needed for painting the text.
+  bool isLowPriorityLoadingAllowedForRemoteFont() const;
+
  private:
   class FontResourceFactory : public ResourceFactory {
    public:
     FontResourceFactory() : ResourceFactory(Resource::Font) {}
 
     Resource* create(const ResourceRequest& request,
                      const ResourceLoaderOptions& options,
                      const String& charset) const override {
       return new FontResource(request, options);
     }
@@ skipping 25 matching lines @@
 
 class FontResourceClient : public ResourceClient {
  public:
   ~FontResourceClient() override {}
   static bool isExpectedType(ResourceClient* client) {
     return client->getResourceClientType() == FontType;
   }
   ResourceClientType getResourceClientType() const final { return FontType; }
   virtual void fontLoadShortLimitExceeded(FontResource*) {}
   virtual void fontLoadLongLimitExceeded(FontResource*) {}
+
+  // Returns true if loading priority of remote font resources can be lowered.
+  virtual bool isLowPriorityLoadingAllowedForRemoteFont() const {
+    // Only the RemoteFontFaceSources clients can prevent lowering of loading
+    // priority of the remote fonts.  Set the default to true to prevent
+    // other clients from incorrectly returning false.
+    return true;
+  }
 };
 
 }  // namespace blink
 
 #endif