Revert of Implement DisplayList GatherPixelRefs

cc/resources/display_item_list.cc

Index: cc/resources/display_item_list.cc
diff --git a/cc/resources/display_item_list.cc b/cc/resources/display_item_list.cc
index 26ff003f0e535b1b603f0b33e612b0675d50fdd5..f8ffbfd184b719d447447b35d58a867ec42d3940 100644
--- a/cc/resources/display_item_list.cc
+++ b/cc/resources/display_item_list.cc
@@ -143,14 +143,4 @@
       "cc::DisplayItemList", this, AsValue());
 }
 
-void DisplayItemList::GatherPixelRefs(const gfx::Size& grid_cell_size) {
-  // This should be only called once, and only after CreateAndCacheSkPicture.
-  DCHECK(picture_);
-  DCHECK(!pixel_refs_);
-  pixel_refs_ = make_scoped_ptr(new PixelRefMap(grid_cell_size));
-  if (!picture_->willPlayBackBitmaps())
-    return;
-
-  pixel_refs_->GatherPixelRefsFromPicture(picture_.get());
-}
 }  // namespace cc