From 01b1e6af97a447cfd561c4a89c49bf2e475d08e2 Mon Sep 17 00:00:00 2001
From: Nicolas Silva <nsilva@mozilla.com>
Date: Tue, 15 Sep 2015 17:58:06 +0200
Subject: [PATCH] Bug 1156182 - Prevent widgets from creating a LayerManager
 during shutdown. r=sotaro

---
 widget/gtk/nsWindow.cpp | 5 +++++
 widget/nsBaseWidget.cpp | 4 ++++
 2 files changed, 9 insertions(+)

diff --git a/widget/gtk/nsWindow.cpp b/widget/gtk/nsWindow.cpp
index 17f2a6ee821..5c5639759ff 100644
--- a/widget/gtk/nsWindow.cpp
+++ b/widget/gtk/nsWindow.cpp
@@ -6542,6 +6542,11 @@ nsWindow::GetLayerManager(PLayerTransactionChild* aShadowManager,
                           LayerManagerPersistence aPersistence,
                           bool* aAllowRetaining)
 {
+    if (mIsDestroyed) {
+      // Prevent external code from triggering the re-creation of the LayerManager/Compositor
+      // during shutdown. Just return what we currently have, which is most likely null.
+      return mLayerManager;
+    }
     if (!mLayerManager && eTransparencyTransparent == GetTransparencyMode()) {
         mLayerManager = CreateBasicLayerManager();
     }
diff --git a/widget/nsBaseWidget.cpp b/widget/nsBaseWidget.cpp
index b788cbc6f12..cf40f46c6c6 100644
--- a/widget/nsBaseWidget.cpp
+++ b/widget/nsBaseWidget.cpp
@@ -1146,6 +1146,10 @@ LayerManager* nsBaseWidget::GetLayerManager(PLayerTransactionChild* aShadowManag
                                             bool* aAllowRetaining)
 {
   if (!mLayerManager) {
+    if (!mShutdownObserver) {
+      // We are shutting down, do not try to re-create a LayerManager
+      return nullptr;
+    }
     // Try to use an async compositor first, if possible
     if (ShouldUseOffMainThreadCompositing()) {
       // e10s uses the parameter to pass in the shadow manager from the TabChild