Fix Resource Priorities and Scheduling (Blink Side)

Source/core/frame/Settings.in

 # Defines properties which are available on the Settings object.
 #
 # Please think carefully before adding a new Setting.  Some questions to
 # consider are:
 # - Should this be a RuntimeEnabledFeature instead? Settings are for things
 #   which we support either values of at runtime.  Features are set at renderer
 #   process startup and are never changed. Features also tend to be set to a
 #   value based on the platform or the stability of the code in question, where
 #   as settings both codepaths need to be stable.
 # - How will you ensure test coverage of all relevant values of your setting?
@@ skipping 345 matching lines @@
 
 lowPriorityIframes initial=false
 
 reportWheelOverscroll initial=false
 
 mainResourceOnlyProgress initial=false
 
 # Do we want to try to save screen real estate in the media player by hiding
 # the volume slider / mute button?
 preferHiddenVolumeControls initial=false
+
+# Controls for resource fetch prioritization.
+# Overall rationale and details here: https://docs.google.com/document/d/1bCDuq9H1ih9iNjgzyAL0gpwNFiEP4TZS-YLRp_RuMlc/edit?usp=sharing
+fetchDeferLateScripts initial=false
+fetchIncreaseFontPriority initial=false
+fetchIncreaseAsyncScriptPriority initial=false
+# Increases the priorities for CSS, Scripts, Fonts and Images all by one level
+# and parser-blocking scripts and visible images by 2.
+# This is used in conjunction with logic on the Chrome side to raise the threshold
+# of "layout-blocking" resources and provide a boost to resources that are needed
+# as soon as possible for something currently on the screen.
+fetchIncreasePriorities initial=false