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

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

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef PaintPropertyTreeBuilder_h
 #define PaintPropertyTreeBuilder_h
 
 #include "platform/geometry/LayoutPoint.h"
 #include "platform/graphics/paint/ClipPaintPropertyNode.h"
 #include "platform/graphics/paint/EffectPaintPropertyNode.h"
@@ skipping 92 matching lines @@
   // Update the paint properties that affect this object (e.g., properties like
   // paint offset translation) and ensure the context is up to date. Also
   // handles updating the object's paintOffset.
   void updatePropertiesForSelf(const LayoutObject&,
                                PaintPropertyTreeBuilderContext&);
   // Update the paint properties that affect children of this object (e.g.,
   // scroll offset transform) and ensure the context is up to date.
   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&);
   ALWAYS_INLINE static void updatePaintOffsetTranslation(
       const LayoutBoxModelObject&,
       PaintPropertyTreeBuilderContext&);
   ALWAYS_INLINE static void updateForObjectLocationAndSize(
       const LayoutObject&,
       PaintPropertyTreeBuilderContext&);
   ALWAYS_INLINE static void updateTransform(const LayoutObject&,
@@ skipping 25 matching lines @@
       const LayoutObject&,
       PaintPropertyTreeBuilderContext&);
   ALWAYS_INLINE static void updateOutOfFlowContext(
       const LayoutObject&,
       PaintPropertyTreeBuilderContext&);
 };
 
 }  // namespace blink
 
 #endif  // PaintPropertyTreeBuilder_h