Use same layout logic in animations for deciding whether an element can transform

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

Index: third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
index 1a2ac756ebe0ce1ecfac18df0090bdcd735442e3..f64ce75366367004c5e0a077494d85dd8b6d6aff 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -133,7 +133,7 @@ void PaintPropertyTreeBuilder::updateTransform(const LayoutObject& object, Paint
         }
     } else {
         const ComputedStyle& style = object.styleRef();
-        if (object.isBox() && (style.hasTransform() || style.preserves3D())) {
+        if (object.canTransformOnCompositor() && (style.hasTransform() || style.preserves3D())) {

[trchen, 2016/08/09 21:57:13]

Hmm... Since you changed the semantics of the function to
canTransformOnCompositor(). I think we should leave it as-is (object.isBox())
for here and below.

FYI this class PaintPropertyTreeBuilder is for generating property trees for
SPv2, and the compositing architecture changed a lot in SPv2. Basically we
delayed compositing decision to a very late stage in the pipeline. The transform
nodes will be always generated, but whether layers need to be created are solely
on cc's discretion.

             TransformationMatrix matrix;
             style.applyTransform(matrix, toLayoutBox(object).size(), ComputedStyle::ExcludeTransformOrigin,
                 ComputedStyle::IncludeMotionPath, ComputedStyle::IncludeIndependentTransformProperties);
@@ -275,7 +275,7 @@ static FloatPoint perspectiveOrigin(const LayoutBox& box)
 void PaintPropertyTreeBuilder::updatePerspective(const LayoutObject& object, PaintPropertyTreeBuilderContext& context)
 {
     const ComputedStyle& style = object.styleRef();
-    if (!object.isBox() || !style.hasPerspective()) {
+    if (!object.canTransformOnCompositor() || !style.hasPerspective()) {
         if (ObjectPaintProperties* properties = object.getMutableForPainting().objectPaintProperties())
             properties->clearPerspective();
         return;