Reuse cc::PictureLayers when possible for SPv2.

third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.cpp

Index: third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.cpp b/third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.cpp
index 528f31b886948436f746505e57ddf1a07b3a61bc..f4d169178cace4f93cd969b0ece46d0f2719889d 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/PaintArtifact.cpp
@@ -21,16 +21,15 @@ void computeChunkBoundsAndOpaqueness(const DisplayItemList& displayItems, Vector
         FloatRect bounds;
         SkRegion knownToBeOpaqueRegion;
         for (const DisplayItem& item : displayItems.itemsInPaintChunk(chunk)) {
+            bounds.unite(FloatRect(item.client().visualRect()));
             if (!item.isDrawing())
                 continue;
             const auto& drawing = static_cast<const DrawingDisplayItem&>(item);
             if (const SkPicture* picture = drawing.picture()) {
-                const SkRect& pictureRect = picture->cullRect();
-                bounds.unite(pictureRect);
                 if (drawing.knownToBeOpaque()) {
-                    // TODO(pdr): This may be too conservative and fail due to
-                    // floating point precision issues.
+                    // TODO(pdr): It may be too conservative to round in to the enclosedIntRect.
                     SkIRect conservativelyRoundedPictureRect;
+                    const SkRect& pictureRect = picture->cullRect();
                     pictureRect.roundIn(&conservativelyRoundedPictureRect);
                     knownToBeOpaqueRegion.op(conservativelyRoundedPictureRect, SkRegion::kUnion_Op);
                 }