Constify SkPicture in DrawingDisplayItem (cc side)

cc/resources/drawing_display_item.cc

Index: cc/resources/drawing_display_item.cc
diff --git a/cc/resources/drawing_display_item.cc b/cc/resources/drawing_display_item.cc
index 0fe86f40d272098922a360cc00caf6b13912d47f..9a0f9ce978292040c1d3841b6deb9150cd4c2ce2 100644
--- a/cc/resources/drawing_display_item.cc
+++ b/cc/resources/drawing_display_item.cc
@@ -17,9 +17,8 @@
 
 namespace cc {
 
-DrawingDisplayItem::DrawingDisplayItem(skia::RefPtr<SkPicture> picture,
-                                       gfx::PointF location)
-    : picture_(picture), location_(location) {
+DrawingDisplayItem::DrawingDisplayItem(skia::RefPtr<const SkPicture> picture)
+    : picture_(picture) {
 }
 
 DrawingDisplayItem::~DrawingDisplayItem() {
@@ -28,7 +27,7 @@ DrawingDisplayItem::~DrawingDisplayItem() {
 void DrawingDisplayItem::Raster(SkCanvas* canvas,
                                 SkDrawPictureCallback* callback) const {
   canvas->save();
-  canvas->translate(location_.x(), location_.y());
+  canvas->translate(picture_->cullRect().x(), picture_->cullRect().y());
   if (callback)
     picture_->playback(canvas, callback);
   else
@@ -38,7 +37,7 @@ void DrawingDisplayItem::Raster(SkCanvas* canvas,
 
 void DrawingDisplayItem::RasterForTracing(SkCanvas* canvas) const {
   canvas->save();
-  canvas->translate(location_.x(), location_.y());
+  canvas->translate(picture_->cullRect().x(), picture_->cullRect().y());
   // The picture debugger in about:tracing doesn't drill down into |drawPicture|
   // operations. Calling |playback()| rather than |drawPicture()| causes the
   // skia operations in |picture_| to appear individually in the picture