Mouse wheel events stop working between Chromium 47.0.2503.0 and 47.0.2522.1

[Chris Coulson]

Upgrading Chromium on trunk causes mouse wheel events to stop working. I'm not sure exactly when this stopped working

[Chris Coulson (chrisccoulson)]

It looks like a scroll animation is never created when the event is passed to the compositor. If I break in the for-loop in LayerTreeHostImpl::ScrollAnimated, just after |actual_delta| is calculated:

      gfx::ScrollOffset current_offset = layer_impl->CurrentScrollOffset();
      gfx::ScrollOffset target_offset =
          ScrollOffsetWithDelta(current_offset, pending_delta);
      target_offset.SetToMax(gfx::ScrollOffset());
      target_offset.SetToMin(layer_impl->MaxScrollOffset());
      gfx::Vector2dF actual_delta = target_offset.DeltaFrom(current_offset);

      const float kEpsilon = 0.1f;
      bool can_layer_scroll = (std::abs(actual_delta.x()) > kEpsilon ||
                               std::abs(actual_delta.y()) > kEpsilon);

(gdb) p actual_delta
$65 = {x_ = 0, y_ = 0}
(gdb) p target_offset
$66 = {x_ = 0, y_ = 53.333332061767578}
(gdb) p current_offset
$67 = {x_ = 0, y_ = 0}

The value of |actual_delta| looks bogus

[Chris Coulson (chrisccoulson)]

Oh, this is broken in Chrome too

[Chris Coulson (chrisccoulson)]

Comment 1 is a red herring - LayerImpl::MaxScrollOffset() actually returns (0,0), so the value of |actual_delta| is correct. I bet this is introduced by https://chromium.googlesource.com/chromium/src.git/+/a3f3a946c870e0d04e7f64049ac0ac3ddea24d24%5E!/

[Chris Coulson (chrisccoulson)]

This is fixed in Chromium 4.0.2523.0

[Chris Coulson (chrisccoulson)]

It's not fixed, I don't know why I thought that

[Chris Coulson (chrisccoulson)]

This still exists in Chrome beta, albeit it requires smooth scrolling to be enabled which is not the default. Given that smooth scrolling is still an experimental feature, I wonder whether we should disable it in Oxide for now.

[minple (fminple)]

please disable smooth or option to disable!