cc: Delete unused DisplayItem::GetPicture func

cc/playback/drawing_display_item.cc

Index: cc/playback/drawing_display_item.cc
diff --git a/cc/playback/drawing_display_item.cc b/cc/playback/drawing_display_item.cc
index 15700830a58266573547c83e7e6e65dd6adfaa3c..d5683105c5fa6422b30ef137eaeebff7c2b4ad01 100644
--- a/cc/playback/drawing_display_item.cc
+++ b/cc/playback/drawing_display_item.cc
@@ -42,10 +42,6 @@ void DrawingDisplayItem::SetNew(sk_sp<const SkPicture> picture) {
   picture_ = std::move(picture);
 }
 
-sk_sp<const SkPicture> DrawingDisplayItem::GetPicture() const {
-  return picture_;
-}
-
 DISABLE_CFI_PERF
 void DrawingDisplayItem::Raster(SkCanvas* canvas,
                                 SkPicture::AbortCallback* callback) const {