From 80ffba5a9ea1ca60a097aac6ce0ad4ce2d5a2f70 Mon Sep 17 00:00:00 2001
From: Ethan Lin <ethlin@mozilla.com>
Date: Mon, 7 Aug 2017 10:10:58 +0800
Subject: [PATCH] Bug 1387455 - Add nullptr check for the draw target in
 WebRenderLayerManager::GenerateFallbackData. r=kats

MozReview-Commit-ID: Dk8WiqOmA1y

--HG--
extra : rebase_source : 91f66b56b70e7cf6401baed1a84fa63bc422dc8b
---
 gfx/layers/wr/WebRenderLayerManager.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/gfx/layers/wr/WebRenderLayerManager.cpp b/gfx/layers/wr/WebRenderLayerManager.cpp
index bd98b1f81372..83d56ce8c182 100644
--- a/gfx/layers/wr/WebRenderLayerManager.cpp
+++ b/gfx/layers/wr/WebRenderLayerManager.cpp
@@ -378,6 +378,8 @@ PaintItemByDrawTarget(nsDisplayItem* aItem,
                       const LayerPoint& aOffset,
                       nsDisplayListBuilder* aDisplayListBuilder)
 {
+  MOZ_ASSERT(aDT);
+
   aDT->ClearRect(aImageRect.ToUnknownRect());
   RefPtr<gfxContext> context = gfxContext::CreateOrNull(aDT, aOffset.ToUnknownPoint());
   MOZ_ASSERT(context);
@@ -483,6 +485,9 @@ WebRenderLayerManager::GenerateFallbackData(nsDisplayItem* aItem,
         UpdateImageHelper helper(imageContainer, imageClient, imageSize.ToUnknownSize(), format);
         {
           RefPtr<gfx::DrawTarget> dt = helper.GetDrawTarget();
+          if (!dt) {
+            return nullptr;
+          }
           PaintItemByDrawTarget(aItem, dt, aImageRect, aOffset, aDisplayListBuilder);
         }
         if (!helper.UpdateImage()) {