LayerImpl::tryScroll must convert its content-space point to layer space before comparing to the no…

cc/layer_impl.cc

Index: cc/layer_impl.cc
diff --git a/cc/layer_impl.cc b/cc/layer_impl.cc
index 6db7af763c2e12d4965ff40862a007824f0484d7..c912bfd85ddf5f3c92075d88777c2263476d4edd 100644
--- a/cc/layer_impl.cc
+++ b/cc/layer_impl.cc
@@ -215,8 +215,9 @@ InputHandlerClient::ScrollStatus LayerImpl::tryScroll(const gfx::PointF& screenS
 
     if (!nonFastScrollableRegion().IsEmpty()) {
         bool clipped = false;
-        gfx::PointF hitTestPointInLocalSpace = MathUtil::projectPoint(screenSpaceTransform().inverse(), screenSpacePoint, clipped);
-        if (!clipped && nonFastScrollableRegion().Contains(gfx::ToFlooredPoint(hitTestPointInLocalSpace))) {
+        gfx::PointF hitTestPointInContentSpace = MathUtil::projectPoint(screenSpaceTransform().inverse(), screenSpacePoint, clipped);
+        gfx::PointF hitTestPointInLayerSpace = hitTestPointInContentSpace.Scale(1 / contentsScaleX(), 1 / contentsScaleY());
+        if (!clipped && nonFastScrollableRegion().Contains(gfx::ToFlooredPoint(hitTestPointInLayerSpace))) {

[enne (OOO), 2012/11/06 23:18:58]

Can you convince me about the use of ToFlooredPoint here?

What if the contents scale of a layer is < 1, do we need to do
Contains(gfx::Rect)?

[danakj, 2012/11/06 23:21:57]

I think I did ToFloored because I wanted no behaviour changes in the gfx::
conversion.

I believe ToRoundedPoint would be better, we want to be as close to their
pointer/finger as possible.
I don't think so. We want to know if it contains the center of the rect, still,
I believe. Just cuz the scale is < 1, doesn't mean we want to make the
pointer/touch point larger.

[danakj, 2012/11/06 23:22:27]

Done.

             TRACE_EVENT0("cc", "LayerImpl::tryScroll: Failed nonFastScrollableRegion");
             return InputHandlerClient::ScrollOnMainThread;
         }