Bug 803826 - Only reset the layer builder pointer in ~ClippedDisplayItem. r=mattwoodrow, a=bajaj

PaintInactiveLayer was resetting the layer manager's layer builder pointer, but
this was unnecessary as this was also being done on destruction of the
ClippedDisplayItem.

layout/base/FrameLayerBuilder.cpp

@@ -1928,8 +1928,7 @@ PaintInactiveLayer(nsDisplayListBuilder* aBuilder,
   if (builder) {
     builder->DidEndTransaction();
   }
- 
-  basic->SetUserData(&gLayerManagerLayerBuilder, NULL);
+
 #ifdef MOZ_DUMP_PAINTING
   if (gfxUtils::sDumpPainting) {
     DumpPaintedImage(aItem, surf);
@@ -2341,7 +2340,7 @@ FrameLayerBuilder::AddThebesDisplayItem(ThebesLayer* aLayer,
     ClippedDisplayItem* cdi =
       entry->mItems.AppendElement(ClippedDisplayItem(aItem, aClip,
                                                      mContainerLayerGeneration));
-    cdi->mInactiveLayer = tempManager;
+    cdi->mInactiveLayerManager = tempManager;
   }
 }
 
@@ -2402,11 +2401,11 @@ FrameLayerBuilder::StoreDataForFrame(nsIFrame* aFrame,
 
 FrameLayerBuilder::ClippedDisplayItem::~ClippedDisplayItem()
 {
-  if (mInactiveLayer) {
+  if (mInactiveLayerManager) {
     // We always start a transaction during layer construction for all inactive
     // layers, but we don't necessarily call EndTransaction during painting.
     // If the transaaction is still open, end it to avoid assertions.
-    BasicLayerManager* basic = static_cast<BasicLayerManager*>(mInactiveLayer.get());
+    BasicLayerManager* basic = static_cast<BasicLayerManager*>(mInactiveLayerManager.get());
     if (basic->InTransaction()) {
       basic->EndTransaction(nullptr, nullptr);
     }
@@ -3156,8 +3155,8 @@ FrameLayerBuilder::DrawThebesLayer(ThebesLayer* aLayer,
       }
     }
 
-    if (cdi->mInactiveLayer) {
-      PaintInactiveLayer(builder, cdi->mInactiveLayer, cdi->mItem, aContext, rc);
+    if (cdi->mInactiveLayerManager) {
+      PaintInactiveLayer(builder, cdi->mInactiveLayerManager, cdi->mItem, aContext, rc);
     } else {
       nsIFrame* frame = cdi->mItem->GetUnderlyingFrame();
       if (frame) {

layout/base/FrameLayerBuilder.h

@@ -605,7 +605,7 @@ protected:
      * layer, then this stores the layer manager being
      * used for the inactive transaction.
      */
-    nsRefPtr<LayerManager> mInactiveLayer;
+    nsRefPtr<LayerManager> mInactiveLayerManager;
 
     Clip mClip;
     uint32_t mContainerLayerGeneration;