Record the set of widgets that contributed to each layer in the Raster stats tool

[kenzieschmoll]

Right now, we only have an image of the layer to guide users to the code in their app that may have contributed to it. Instead, we should provide them with the set of widgets that contributed to each layer.

@iskakaushik was working on this at one point, and another option we discussed was providing the set of render objects, or in the future, providing a set of draw commands that we could replay in DevTools to show their cost.

[kenzieschmoll]

From an offline discussion with @jacob314. Posting here to track.

There is a fine mapping from render objects to widgets although you might have to add a flag to enable it in profile mode, etc. There should be ways to do all or almost all of it in the framework side. Basically just flow back unique ids for the layers from the engine, and then do the rest of the logic in the framework. For example here is where each widget tracks its layer

• https://github.com/flutter/flutter/blob/3.14.0-12.0.pre/packages/flutter/lib/src/rendering/object.dart#L2788

and here is all it takes given a renderObject to get the Element (if you are in debug)

• https://github.com/flutter/flutter/blob/3.14.0-12.0.pre/packages/flutter/lib/src/widgets/widget_inspector.dart#L2942

[kenzieschmoll]

This feature has been removed from DevTools, so closing this as obsolete.