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

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

Comment on attachment 8393023 [details] 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.

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+

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