982196 - Make the ReflowHelper listen on 'developer-hud-update' events

Status: RESOLVED FIXED

(Firefox OS Graveyard :: Gaia::TestAgent, defect)

Description

[Jan Keromnes [:janx]]

When the Developer HUD has a nicer API, use it in the ReflowHelper.

To update the reflow count of an app, simply listen for the 'developer-hud-update' event on the System App:
- Check that `event.detail.metric === 'reflows'`
- The app's manifest url is `event.detail.manifest`
- The frame that caused the reflow is `event.target`
- The total number of reflows for that app is `event.detail.value`

You will need the following prefs:
- devtools.debugger.forbid-certified-apps: false
- devtools.overlay: true
- hud.reflows: true

Comment 1

[Etienne Segonzac (:etienne)]

Attachment: Gaia PR

Awesome, I'm basically removing all the code :)

Comment 2

[Jan Keromnes [:janx]]

Comment on attachment 8393023 [details] [review]
Gaia PR

Indeed! Looks much better now.

You could also make the code smaller still by removing the `reflowWatcher` object entirely, using only `count` and `trackingManifest` as state variables, and performing the state changes directly in the atom functions plus an event listener function.

Comment 3

[Jan Keromnes [:janx]]

Thanks for addressing my nit!
I still prefer scoped variables to object members, and calling `addEventListener` directly in the main closure rather than defining a `MozReflowAtom.init()` method, but that's just me :) r+

Comment 4

[Etienne Segonzac (:etienne)]

https://github.com/mozilla-b2g/gaia/commit/6366b3a81d604152c2030ab6e58eed29c614aa85

Comment 5

[Kevin Grandon :kgrandon]

We uplifted this into 1.4 in the hope that this will fix an intermittent error that we are seeing in bug 982196.

https://github.com/mozilla-b2g/gaia/commit/b7216ec7bcbe14e49a3869e369a85b674d3079c1