Bugzilla

We don't yet have guidance on the toolbar button / page action button, how it will look, where it will live (page action vs toolbar button), or how it will behave.

This is a placeholder bug to hold the final decision from UX when available.

This bug covers creating a shopping page action button.

If the shopping experience is enabled, that is, `browser.shopping.experience2023.enabled` is true, then this button should appear in the URLBar when the user visits a supported product page.

If the shopping experience is disabled, that is, `browser.shopping.experience2023.enabled` is false, we don't want to show the page action button at all.

There is a pref that tells us whether a user has opted in or out of the experience, `browser.shopping.experience2023.optedIn`. (Note this is different from the `browser.shopping.experience2023.enabled` pref, which simply puts a user in the experimental population that might be shown the experience.)

If the `browser.shopping.experience2023.optedIn` pref value is false, then when the user visits a supported shopping page, we want to display the shopping page action button in an inactive state. (The sidebar will not pop open automatically in this case.)

If the `browser.shopping.experience2023.optedIn` pref value is true, then when the user visits a supported product page, the page action button will be shown in an active state, and the sidebar will appear.

Whenever the user clicks the page action button, the `browser.shopping.experience2023.optedIn` pref value should be flipped (note, this behavior may change in the next few days), and the button should toggle between active/inactive states.

Figma designs: https://www.figma.com/file/Wu4kaHSfKSQnzkym7qek3R/Shopping-Experience-MVP?type=design&node-id=67-23327&mode=design&t=VvOstFKWe7hwylJc-4

To notify your button component when the user arrives on a product page, you can make a call directly from either branch of the `if (this._isProductPage)` conditional [here](https://searchfox.org/mozilla-central/rev/f29deb388a7675b93f040b0e89a37822cdbd8d58/browser/base/content/browser.js#9991), inside the onLocationChange listener.

Explicit non-goals for this bug:
* we don't yet have a final icon, so don't spend too much time styling the placeholder shopping cart svg; flipping a color is enough.
* after the page action button is clicked, the sidebar toggling behavior is still not fully signed off, but flipping the pref is a good enough guess for now.

Implementation notes:

To notify your button component when the user arrives on a product page, you can make a call directly from either branch of the `if (this._isProductPage)` conditional [here](https://searchfox.org/mozilla-central/rev/f29deb388a7675b93f040b0e89a37822cdbd8d58/browser/base/content/browser.js#9991).

I would guess Gijs is the right person to review patches, as he's familiar with toolbar button code (I'm not sure if anyone else on the team is).