--- a/gfx/thebes/gfxPrefs.h
+++ b/gfx/thebes/gfxPrefs.h
@@ -659,16 +659,17 @@ private:
   DECL_GFX_PREF(Live, "layout.css.scroll-behavior.enabled",    ScrollBehaviorEnabled, bool, true);
   DECL_GFX_PREF(Live, "layout.css.scroll-behavior.spring-constant", ScrollBehaviorSpringConstant, float, 250.0f);
   DECL_GFX_PREF(Live, "layout.css.scroll-snap.prediction-max-velocity", ScrollSnapPredictionMaxVelocity, int32_t, 2000);
   DECL_GFX_PREF(Live, "layout.css.scroll-snap.prediction-sensitivity", ScrollSnapPredictionSensitivity, float, 0.750f);
   DECL_GFX_PREF(Live, "layout.css.scroll-snap.proximity-threshold", ScrollSnapProximityThreshold, int32_t, 200);
   DECL_GFX_PREF(Live, "layout.css.touch_action.enabled",       TouchActionEnabled, bool, false);
   DECL_GFX_PREF(Live, "layout.display-list.dump",              LayoutDumpDisplayList, bool, false);
   DECL_GFX_PREF(Live, "layout.display-list.dump-content",      LayoutDumpDisplayListContent, bool, false);
+  DECL_GFX_PREF(Live, "layout.display-list.dump-parent",       LayoutDumpDisplayListParent, bool, false);
   DECL_GFX_PREF(Live, "layout.event-regions.enabled",          LayoutEventRegionsEnabledDoNotUseDirectly, bool, false);
   DECL_GFX_PREF(Once, "layout.frame_rate",                     LayoutFrameRate, int32_t, -1);
   DECL_GFX_PREF(Live, "layout.min-active-layer-size",          LayoutMinActiveLayerSize, int, 64);
   DECL_GFX_PREF(Once, "layout.paint_rects_separately",         LayoutPaintRectsSeparately, bool, true);
 
   // This and code dependent on it should be removed once containerless scrolling looks stable.
   DECL_GFX_PREF(Once, "layout.scroll.root-frame-containers",   LayoutUseContainersForRootFrames, bool, true);
   // This pref is to be set by test code only.

--- a/gfx/thebes/gfxUtils.cpp
+++ b/gfx/thebes/gfxUtils.cpp
@@ -1478,16 +1478,17 @@ gfxUtils::ThreadSafeGetFeatureStatus(con
   }
 
   return gfxInfo->GetFeatureStatus(feature, failureId, status);
 }
 
 /* static */ bool
 gfxUtils::DumpDisplayList() {
   return gfxPrefs::LayoutDumpDisplayList() ||
+         (gfxPrefs::LayoutDumpDisplayListParent() && XRE_IsParentProcess()) ||
          (gfxPrefs::LayoutDumpDisplayListContent() && XRE_IsContentProcess());
 }
 
 FILE *gfxUtils::sDumpPaintFile = stderr;
 
 namespace mozilla {
 namespace gfx {
 

--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -3120,16 +3120,17 @@ pref("layout.interruptible-reflow.enable
 // pref to control browser frame rate, in Hz. A value <= 0 means choose
 // automatically based on knowledge of the platform (or 60Hz if no platform-
 // specific information is available).
 pref("layout.frame_rate", -1);
 
 // pref to dump the display list to the log. Useful for debugging drawing.
 pref("layout.display-list.dump", false);
 pref("layout.display-list.dump-content", false);
+pref("layout.display-list.dump-parent", false);
 
 // pref to control whether layout warnings that are hit quite often are enabled
 pref("layout.spammy_warnings.enabled", false);
 
 // Should we fragment floats inside CSS column layout?
 pref("layout.float-fragments-inside-column.enabled", true);
 
 // The number of frames times the frame rate is the time required to