Store previous painting clip rects on FragmentData.

third_party/WebKit/Source/core/paint/PaintLayer.h

Index: third_party/WebKit/Source/core/paint/PaintLayer.h
diff --git a/third_party/WebKit/Source/core/paint/PaintLayer.h b/third_party/WebKit/Source/core/paint/PaintLayer.h
index 9f8ea182f0cf03edc2d9440096036c90022fbef7..aaa4f77563d66381a7a303a23dcb2681b502b9cd 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayer.h
+++ b/third_party/WebKit/Source/core/paint/PaintLayer.h
@@ -925,15 +925,14 @@ class CORE_EXPORT PaintLayer : public DisplayItemClient {
     previous_scroll_offset_accumulation_for_painting_ = s;
   }
 
-  ClipRects* PreviousPaintingClipRects() const {
-    return previous_painting_clip_rects_.Get();
+  ClipRects* PreviousClipRects() const {
+    DCHECK(!RuntimeEnabledFeatures::slimmingPaintInvalidationEnabled());
+    return previous_clip_rects_.Get();
   }
-  void SetPreviousPaintingClipRects(ClipRects& clip_rects) {
-    previous_painting_clip_rects_ = &clip_rects;
-  }
-  void ClearPreviousPaintingClipRects() {
-    previous_painting_clip_rects_.Clear();
+  void SetPreviousClipRects(ClipRects& clip_rects) {
+    previous_clip_rects_ = &clip_rects;

[wkorman, 2017/05/01 21:58:09]

Will this do the right thing re: RefPtr? I'd think we have to pass PassRefPtr as
param for the counting to do what's intended.

My concern is re: who owns the memory allocated for the inputted clip_rects. Do
we have any assurance the caller won't deallocate but we'll keep our ref here.

But I actually couldn't find any documentation on PassRefPtr or RefPtr just now
when I looked.

[chrishtr, 2017/05/01 22:40:07]

The memory is owned by the PaintLayer or FragmentData. It does work but I agree
it's a bit
weird looking. I had to research it when I first found it also.

   }
+  void ClearPreviousClipRects() { previous_clip_rects_.Clear(); }
 
   LayoutRect PreviousPaintDirtyRect() const {
     return previous_paint_dirty_rect_;
@@ -1265,7 +1264,7 @@ class CORE_EXPORT PaintLayer : public DisplayItemClient {
   std::unique_ptr<PaintLayerStackingNode> stacking_node_;
 
   IntSize previous_scroll_offset_accumulation_for_painting_;
-  RefPtr<ClipRects> previous_painting_clip_rects_;
+  RefPtr<ClipRects> previous_clip_rects_;
   LayoutRect previous_paint_dirty_rect_;
 
   std::unique_ptr<PaintLayerRareData> rare_data_;