Optimize CompositingRecorder::endCompositing to not need an SkPictureBuilder

third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp b/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp
index da4423323e9ad1c61188ac8dadf3b151378362ee..346da44970af9afc5f71996d30ba3bd14c7337ca 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/DrawingRecorder.cpp
@@ -20,11 +20,6 @@ DrawingRecorder::DrawingRecorder(GraphicsContext& context,
       m_displayItemClient(displayItemClient),
       m_displayItemType(displayItemType),
       m_knownToBeOpaque(false)
-#if DCHECK_IS_ON()
-      ,
-      m_displayItemPosition(
-          m_context.getPaintController().newDisplayItemList().size())
-#endif
 {
   if (context.getPaintController().displayItemConstructionIsDisabled())
     return;
@@ -73,10 +68,7 @@ DrawingRecorder::~DrawingRecorder() {
 #if DCHECK_IS_ON()
   if (RuntimeEnabledFeatures::slimmingPaintStrictCullRectClippingEnabled())
     m_context.restore();
-
   m_context.setInDrawingRecorder(false);
-  DCHECK(m_displayItemPosition ==

[chrishtr, 2017/02/02 23:52:07]

This DCHECK still seems generally useful. Pass an extra arg
to suppress it for CompositingRecorder?

-         m_context.getPaintController().newDisplayItemList().size());
 #endif
 
   sk_sp<const SkPicture> picture = m_context.endRecording();