To reproduce, open http://people.mozilla.org/~bballo/plain.html (plain HTML page with a wide image), with the dynamic toolbar enabled. The scrollbar on the right flickers repeatedly. It looks like a scroll event is being fired repeatedly, which shouldn't be happening.

This is a more recent regression than the original dynamic toolbar code. It only happens on nightly.

The regression window is: 1. mozilla-central: good build: 11.07.2013 bad build: 12.07.2013 -pushlog: http://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=dde4dcd6fa46&tochange=b44898282f21 2. inbound: good build: 1373557796 bad build: 1373562059 -pushlog: http://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=df4cc5d63c7d&tochange=9e018ae9cbed

Thanks.

Note that this still doesn't happen on aurora or beta, so it must be caused by the second (refactoring) patch on bug 877602 which was not uplifted.

Try push at https://tbpl.mozilla.org/?tree=Try&rev=7362360d9a84

Comment on attachment 788960 [details] [diff] [review] Patch Review of attachment 788960 [details] [diff] [review]: ----------------------------------------------------------------- LGTM, I guess. Sorry to have roped you into this :) ::: mobile/android/chrome/content/browser.js @@ +3916,5 @@ > + > + // Store the page size that was used to calculate the viewport so that we > + // can verify it's changed when we consider remeasuring in updateViewportForPageSize > + let viewport = this.getViewport(); > + this.lastPageSizeUsedForViewportChange = { Maybe this should be renamed lastPageSizeAfterViewportRemeasure, perhaps? It doesn't feel like this comment really corresponds to what's actually happening anymore...

I updated the variable name as you suggested. The comment still made sense to me so I left it. https://hg.mozilla.org/integration/fx-team/rev/ec6710da612e

Comment on attachment 788960 [details] [diff] [review] Patch [Approval Request Comment] Bug caused by (feature/regressing bug #): bug 877602 (second patch) User impact if declined: on some pages the code will continue doing layouts infinitely, which is bad for battery life. also the scrollbars will keep flashing. Testing completed (on m-c, etc.): locally; this should bake on m-c for a few days to ensure there's no other fallout Risk to taking this patch (and alternatives if risky): low risk, fennec-only code String or IDL/UUID changes made by this patch: none

Verified fixed on: Build: Firefox for Android 26.0a1 (2013-08-13) Device: HTC Desire HD OS: Android 2.3.5

Verified fixed on: Build: Firefox for Android 25.0a2 (2013-08-27) Device: HTC Desire HD OS: Android 2.3.5