Add an --enable-deferred-filters command-line flag.

content/renderer/web_preferences.cc

Index: content/renderer/web_preferences.cc
diff --git a/content/renderer/web_preferences.cc b/content/renderer/web_preferences.cc
index b3cf5a4f95395b17bc16fe960006181911d59898..6682e6054196d0574c0ee4ba191f4fdb14075760 100644
--- a/content/renderer/web_preferences.cc
+++ b/content/renderer/web_preferences.cc
@@ -243,6 +243,9 @@ void ApplyWebPreferences(const WebPreferences& prefs, WebView* web_view) {
   // Enable gpu-accelerated filters if requested on the command line.
   settings->setAcceleratedFiltersEnabled(prefs.accelerated_filters_enabled);
 
+  // Enable deferred filter rendering if requested on the command line.
+  settings->setDeferredFiltersEnabled(prefs.deferred_filters_enabled);
+
   // Enable gesture tap highlight if requested on the command line.
   settings->setGestureTapHighlightEnabled(prefs.gesture_tap_highlight_enabled);