--- a/gfx/layers/Layers.cpp
+++ b/gfx/layers/Layers.cpp
@@ -214,20 +214,20 @@ LayerManager::AreComponentAlphaLayersEna
 }
 
 /*static*/ void
 LayerManager::LayerUserDataDestroy(void* data)
 {
   delete static_cast<LayerUserData*>(data);
 }
 
-nsAutoPtr<LayerUserData>
+UniquePtr<LayerUserData>
 LayerManager::RemoveUserData(void* aKey)
 {
-  nsAutoPtr<LayerUserData> d(static_cast<LayerUserData*>(mUserData.Remove(static_cast<gfx::UserDataKey*>(aKey))));
+  UniquePtr<LayerUserData> d(static_cast<LayerUserData*>(mUserData.Remove(static_cast<gfx::UserDataKey*>(aKey))));
   return d;
 }
 
 //--------------------------------------------------
 // Layer
 
 Layer::Layer(LayerManager* aManager, void* aImplData) :
   mManager(aManager),
@@ -2143,20 +2143,20 @@ Layer::IsBackfaceHidden()
         return container->GetEffectiveTransform().IsBackfaceVisible();
       }
       return container->GetBaseTransform().IsBackfaceVisible();
     }
   }
   return false;
 }
 
-nsAutoPtr<LayerUserData>
+UniquePtr<LayerUserData>
 Layer::RemoveUserData(void* aKey)
 {
-  nsAutoPtr<LayerUserData> d(static_cast<LayerUserData*>(mUserData.Remove(static_cast<gfx::UserDataKey*>(aKey))));
+  UniquePtr<LayerUserData> d(static_cast<LayerUserData*>(mUserData.Remove(static_cast<gfx::UserDataKey*>(aKey))));
   return d;
 }
 
 void
 PaintedLayer::PrintInfo(std::stringstream& aStream, const char* aPrefix)
 {
   Layer::PrintInfo(aStream, aPrefix);
   if (!mValidRegion.IsEmpty()) {

--- a/gfx/layers/Layers.h
+++ b/gfx/layers/Layers.h
@@ -500,17 +500,17 @@ public:
    */
   void SetUserData(void* aKey, LayerUserData* aData)
   {
     mUserData.Add(static_cast<gfx::UserDataKey*>(aKey), aData, LayerUserDataDestroy);
   }
   /**
    * This can be used anytime. Ownership passes to the caller!
    */
-  nsAutoPtr<LayerUserData> RemoveUserData(void* aKey);
+  UniquePtr<LayerUserData> RemoveUserData(void* aKey);
 
   /**
    * This getter can be used anytime.
    */
   bool HasUserData(void* aKey)
   {
     return mUserData.Has(static_cast<gfx::UserDataKey*>(aKey));
   }
@@ -1457,17 +1457,17 @@ public:
    */
   void SetUserData(void* aKey, LayerUserData* aData)
   {
     mUserData.Add(static_cast<gfx::UserDataKey*>(aKey), aData, LayerManager::LayerUserDataDestroy);
   }
   /**
    * This can be used anytime. Ownership passes to the caller!
    */
-  nsAutoPtr<LayerUserData> RemoveUserData(void* aKey);
+  UniquePtr<LayerUserData> RemoveUserData(void* aKey);
   /**
    * This getter can be used anytime.
    */
   bool HasUserData(void* aKey)
   {
     return mUserData.Has(static_cast<gfx::UserDataKey*>(aKey));
   }
   /**

--- a/gfx/tests/gtest/TestLayers.cpp
+++ b/gfx/tests/gtest/TestLayers.cpp
@@ -145,19 +145,19 @@ TEST(Layers, UserData) {
   TestUserData* data2 = new TestUserData;
   TestUserData* data3 = new TestUserData;
 
   layer.SetUserData(key1, data1);
   layer.SetUserData(key2, data2);
   layer.SetUserData(key3, data3);
 
   // Also checking that the user data is returned but not free'd
-  UniquePtr<LayerUserData> d1(layer.RemoveUserData(key1).forget());
-  UniquePtr<LayerUserData> d2(layer.RemoveUserData(key2).forget());
-  UniquePtr<LayerUserData> d3(layer.RemoveUserData(key3).forget());
+  UniquePtr<LayerUserData> d1(layer.RemoveUserData(key1));
+  UniquePtr<LayerUserData> d2(layer.RemoveUserData(key2));
+  UniquePtr<LayerUserData> d3(layer.RemoveUserData(key3));
   ASSERT_EQ(data1, d1.get());
   ASSERT_EQ(data2, d2.get());
   ASSERT_EQ(data3, d3.get());
 
   layer.SetUserData(key1, d1.release());
   layer.SetUserData(key2, d2.release());
   layer.SetUserData(key3, d3.release());