[Notebook] Example Imagery doesn't capture images

[nikhilmandlik]

Related issues:

1. Notebook Snapshot issues #2940
2. [Notebook] Notebook Snapshot not capturing some DOM elements #1903

This is CORS content policy restrictions issue.

Ideal Solution: Images response header need to have property Access-Control-Allow-Origin with proper value.

Any image with this property missing ll be blocked by canvas capture due to underlying security concerns.

More info available:

html2canvas:
CORS vs Images/canvas:

---

Testing instructions:

ref: snapshot Display Layout -> /stable/#/browse/mine/df4b6619-ea5c-4432-968d-2ca0f3c0debf/d9ebbefc-32ec-4ab6-9d8f-614748a96809?tc.mode=local&tc.startDelta=900000&tc.endDelta=15000&tc.timeSystem=utc&view=layout.view

1. for comparison try same from images on both /testathon (pass) vs /stable (fail)
2. Add images into a display layout
3. Now take a snapshot and open that snapshot
4. confirm that pass images shows up in snapshot

Images/url for testing:

Name	Pass/Fail	source url
Space force	Pass	https://upload.wikimedia.org/wikipedia/commons/thumb/2/29/Seal_of_the_United_States_Space_Force.svg/1200px-Seal_of_the_United_States_Space_Force.svg.png
blade runner 2049	Pass	https://images.theconversation.com/files/188582/original/file-20171003-3782-lzbf76.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=926&fit=clip
Nasa logo	Fail	https://www.nasa.gov/sites/all/themes/custom/nasatwo/images/nasa-logo.svg
Deckard Chases Zhora	Fail	https://variety.com/wp-content/uploads/2013/05/bladerunner_sequel.jpg

[akhenry]

@nikhilmandlik Needs test notes.

[unlikelyzero]

Re-opening

[unlikelyzero]

Closing to test in sprint 1.7.8 testathon

[charlesh88]

Verified fixed Testathon 9-20-21.