An AutofillManager is created for every RenderFrame [1]. On the NTP that means three managers are created (there's iframes). 

We should:
(1) Reconsider creating AutofillManager for chrome:// pages (these days the NTP is at chrome-search://local-ntp) or their children frames 
(2) Consider lazily creating AutofillManager while keeping a Mojo channel up for the renderer to notify of parsed forms.
(3) Generally avoid expensive AutofillManager initializations (are there any?) and move those to a background task.

Assigning to Roger as low priority item but we should probably mitigate this in M65

[1] https://cs.chromium.org/chromium/src/components/autofill/content/browser/content_autofill_driver_factory.cc?type=cs&q=ContentAutofillDriverFactory::RenderFrameCreated&sq=package:chromium&l=123