[SPv2] Decomposite otherwise-compositable animations that paint nothing.

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

Index: third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h
diff --git a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h
index 669ff3e3883d5f678985dcd83cb5e204069b8b0d..c79351b9d684d627469be27263c5bec81f6d9bfd 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.h
@@ -110,6 +110,12 @@ class PaintPropertyTreeBuilder {
   void updatePropertiesForChildren(const LayoutObject&,
                                    PaintPropertyTreeBuilderContext&);
 
+  // Returns a stable compositor element id for the given layout

[pdr., 2017/03/16 21:20:05]

Nit: remove?

[wkorman, 2017/03/16 21:53:31]

Will fix this as part of cleanup, I think we want to share this method's logic
in some manner, exposing it like I have commented out here may be one way, more
soon.

+  // object. Intended for use by the animation subsystem as an opaque identifier
+  // to tie animations to their associated property tree nodes.
+  /* static CompositorElementId createDomNodeBasedCompositorElementId(const
+   * LayoutObject& object); */
+
  private:
   ALWAYS_INLINE static void updatePaintOffset(const LayoutBoxModelObject&,
                                               PaintPropertyTreeBuilderContext&);