Fix CSS reference filters with negative transformed children.

cc/playback/filter_display_item.cc

Index: cc/playback/filter_display_item.cc
diff --git a/cc/playback/filter_display_item.cc b/cc/playback/filter_display_item.cc
index 224d1c80457b790390649679a0cdc7218b108c38..6541433fcfd52d97ceac4757f4184fb421425deb 100644
--- a/cc/playback/filter_display_item.cc
+++ b/cc/playback/filter_display_item.cc
@@ -21,8 +21,9 @@
 namespace cc {
 
 FilterDisplayItem::FilterDisplayItem(const FilterOperations& filters,
-                                     const gfx::RectF& bounds) {
-  SetNew(filters, bounds);
+                                     const gfx::RectF& bounds,
+                                     const SkPoint& origin) {
+  SetNew(filters, bounds, origin);
 }
 
 FilterDisplayItem::FilterDisplayItem(const proto::DisplayItem& proto) {
@@ -33,16 +34,18 @@ FilterDisplayItem::FilterDisplayItem(const proto::DisplayItem& proto) {
 
   // TODO(dtrainor): Support deserializing FilterOperations (crbug.com/541321).
   FilterOperations filters;
-
-  SetNew(filters, bounds);
+  SkPoint origin = SkPoint::Make(0, 0);  // TODO(senorblanco): Support origin.
+  SetNew(filters, bounds, origin);
 }
 
 FilterDisplayItem::~FilterDisplayItem() {}
 
 void FilterDisplayItem::SetNew(const FilterOperations& filters,
-                               const gfx::RectF& bounds) {
+                               const gfx::RectF& bounds,
+                               const SkPoint& origin) {
   filters_ = filters;
   bounds_ = bounds;
+  origin_ = origin;
 }
 
 void FilterDisplayItem::ToProtobuf(proto::DisplayItem* proto) const {
@@ -57,18 +60,19 @@ void FilterDisplayItem::ToProtobuf(proto::DisplayItem* proto) const {
 void FilterDisplayItem::Raster(SkCanvas* canvas,
                                SkPicture::AbortCallback* callback) const {
   canvas->save();
-  canvas->translate(bounds_.x(), bounds_.y());
+  canvas->translate(origin_.x(), origin_.y());
 
   sk_sp<SkImageFilter> image_filter = RenderSurfaceFilters::BuildImageFilter(
       filters_, gfx::SizeF(bounds_.width(), bounds_.height()));
-  SkRect boundaries = SkRect::MakeWH(bounds_.width(), bounds_.height());
+  SkRect boundaries = RectFToSkRect(bounds_);
+  boundaries.offset(-origin_.x(), -origin_.y());
 
   SkPaint paint;
   paint.setXfermodeMode(SkXfermode::kSrcOver_Mode);
   paint.setImageFilter(std::move(image_filter));
   canvas->saveLayer(&boundaries, &paint);
 
-  canvas->translate(-bounds_.x(), -bounds_.y());
+  canvas->translate(-origin_.x(), -origin_.y());

[wkorman, 2016/08/26 17:45:52]

Are we still using bounds_.x/y anywhere? If not maybe we should change it to a
Size for clarity, for example I think this would mean we wouldn't do this
moveBy() unnecessarily any more:

https://cs.chromium.org/chromium/src/third_party/WebKit/Source/core/paint/Fil...

[Stephen White, 2016/08/26 19:22:01]

Yes, we still need a full rect as well as an origin. bounds 
represents the bounding rectangle of the original primitive and 
all its children. origin represents the top/left of the original 
primitive within those bounds, excluding children. So if the parent 
has a negatively transformed child node, (bounds.location() - origin) 
will be non-zero, which we need to pass to saveLayer().

(Notice that origin is used both to translate the CTM to the right 
place, and also to offset the saveLayer() boundaries at line 68).)

[wkorman, 2016/08/26 19:35:25]

Ah, I searched for bounds_ and missed boundaries!

 }
 
 void FilterDisplayItem::AsValueInto(