Further plumb visual rect into cc:DisplayItemList.

cc/playback/display_item_list.h

Index: cc/playback/display_item_list.h
diff --git a/cc/playback/display_item_list.h b/cc/playback/display_item_list.h
index 21422600d8648a6d9ab31f84d5752a811803c98d..b0f49428ff3983d7043208d0530f25b00fc240ec 100644
--- a/cc/playback/display_item_list.h
+++ b/cc/playback/display_item_list.h
@@ -61,10 +61,11 @@ class CC_EXPORT DisplayItemList
   void RasterIntoCanvas(const DisplayItem& display_item);
 
   template <typename DisplayItemType>
-  DisplayItemType* CreateAndAppendItem() {
+  DisplayItemType* CreateAndAppendItem(const gfx::Rect& visual_rect) {
 #if DCHECK_IS_ON()
     needs_process_ = true;
 #endif
+    visual_rects_.push_back(visual_rect);

[wkorman, 2015/11/17 21:49:47]

We could consider not storing these, and clearing them, unless a flag for the
feature is enabled. We have added a flag but it is in Blink
RuntimeEnabledFeatures:

http://crrev.com/1410573008

So I think what we'd want to do is something like:

- add a switch for Chromium side to enable feature for cc/
- somehow tie that switch to enabling the Blink REF
- do the hijinks we need to do to make sure this gets passed between processes
properly

I'm not really happy with what we did for Slimming Paint. chrishtr@ says he has
something similar afoot currently. It's particularly confusing because there are
regular Chromium switches, but also cc/base/switches.cc, and then Blink REF, and
then cc has some cc-specific flag UI, and then there's also the chrome://flags
UI, and then with SP the way we did it involved monkeying web
preferences/settings somehow in a manner that was in fact persistent and I
believe could get users into a state where even with the flag switched off in
the chrome://flags UI they still had at least part of SP enabled permanently
unless they cleared their user profile data.

I think this is fine for now, we can add flag in subsequent change, I wanted to
solicit feedback.

[enne (OOO), 2015/11/17 22:28:20]

I don't think we need a flag for this.  We should make this fast enough and then
land it.

     ProcessAppendedItemsOnTheFly();
     return items_.AllocateAndConstruct<DisplayItemType>();
   }
@@ -113,6 +114,12 @@ class CC_EXPORT DisplayItemList
 #endif
 
   ListContainer<DisplayItem> items_;
+  // The visual rects associated with each of the display items in the
+  // display item list. There is one rect per display item, and the
+  // position in |visual_rects_| matches the position of the item in
+  // |items_| . These rects are intentionally kept separate
+  // because they are not needed while walking the |items_| for raster.
+  std::vector<gfx::Rect> visual_rects_;
   skia::RefPtr<SkPicture> picture_;
 
   scoped_ptr<SkPictureRecorder> recorder_;