From 04a1360805949be066e12a10efe91872d55ec5da Mon Sep 17 00:00:00 2001
From: Miko Mynttinen <mikokm@gmail.com>
Date: Wed, 8 Aug 2018 22:02:34 +0000
Subject: [PATCH] Bug 1413546 - Fix e10s logic in
 nsLayoutUtils::AreRetainedDisplayListsEnabled() and set
 layout.display-list.retain.chrome to true r=mattwoodrow

Differential Revision: https://phabricator.services.mozilla.com/D2953

--HG--
extra : moz-landing-system : lando
---
 layout/base/nsLayoutUtils.cpp | 7 ++++++-
 modules/libpref/init/all.js   | 2 +-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/layout/base/nsLayoutUtils.cpp b/layout/base/nsLayoutUtils.cpp
index 29de8e62c514..ed4a8a489cbe 100644
--- a/layout/base/nsLayoutUtils.cpp
+++ b/layout/base/nsLayoutUtils.cpp
@@ -468,9 +468,14 @@ nsLayoutUtils::AreRetainedDisplayListsEnabled()
 {
   if (XRE_IsContentProcess()) {
     return gfxPrefs::LayoutRetainDisplayList();
-  } else {
+  }
+
+  if (XRE_IsE10sParentProcess()) {
     return gfxPrefs::LayoutRetainDisplayListChrome();
   }
+
+  // Retained display lists require e10s.
+  return false;
 }
 
 bool
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index af54add1cad6..01b776f0a061 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -3077,10 +3077,10 @@ pref("layout.display-list.dump-parent", false);
 // Toggle retaining display lists between paints
 #if !defined(ANDROID)
 pref("layout.display-list.retain", true);
+pref("layout.display-list.retain.chrome", true);
 #else
 pref("layout.display-list.retain", false);
 #endif
-pref("layout.display-list.retain.chrome", false);
 
 // Set the maximum amount of modified frames allowed before doing a full
 // display list rebuild.