Experiment with more aggressive MSE GC on memory pressure

content/public/common/web_preferences.h

Index: content/public/common/web_preferences.h
diff --git a/content/public/common/web_preferences.h b/content/public/common/web_preferences.h
index 9bcda9e87dee064796afa827bf34f6ec94e92085..3778307e77e3b40c3ae1a4322b4a48f2e11d0e05 100644
--- a/content/public/common/web_preferences.h
+++ b/content/public/common/web_preferences.h
@@ -272,6 +272,14 @@ struct CONTENT_EXPORT WebPreferences {
   // the renderer process. See https://crbug.com/681160.
   base::TimeDelta max_keyframe_distance_to_disable_background_video;
 
+  // When memory pressure based garbage collection is enabled for MSE, the
+  // |enable_instant_source_buffer_gc| flag controls whether the GC is done
+  // immediately on memory pressure notification or during the next SourceBuffer
+  // append (slower, but is MSE-spec compliant).
+  // TODO(servolk, asvitkine): Query the value directly when it is available in
+  // the renderer process. See https://crbug.com/681160.
+  bool enable_instant_source_buffer_gc;
+
   // Whether it is a presentation receiver.
   bool presentation_receiver;