Make new-style page scale work on Android.

cc/pinch_zoom_viewport.cc

Index: cc/pinch_zoom_viewport.cc
diff --git a/cc/pinch_zoom_viewport.cc b/cc/pinch_zoom_viewport.cc
index dab6c9ca823cc57b18ef53eb3c503f41a5948813..723cc64814e5ea08055c120473a84fd9cfc859ad 100644
--- a/cc/pinch_zoom_viewport.cc
+++ b/cc/pinch_zoom_viewport.cc
@@ -50,16 +50,15 @@ bool PinchZoomViewport::SetPageScaleFactorAndLimits(
   return true;
 }
 
-gfx::RectF PinchZoomViewport::Bounds() const {
-  gfx::RectF bounds(gfx::PointF(), layout_viewport_size_);
-  bounds.Scale(1 / total_page_scale_factor());
-  bounds += zoomed_viewport_offset_;
-  return bounds;
+gfx::RectF PinchZoomViewport::ZoomedViewport() const {

[danakj, 2013/01/17 18:02:49]

80 cols in this file

+  gfx::SizeF dip_viewport_size = gfx::ScaleSize(device_viewport_size_, 1 / device_scale_factor_);

[danakj, 2013/01/17 18:02:49]

Can we not introduce "dip" in the compositor? I find it ambiguous. Any space
other than physical pixels is dip. I'd much prefer names like "layout viewport"
or "zoomed layout viewport" where the space is clearly defined. And if it's
relative to some space, use that space with a description of its relationship to
it please.

In this case this is the unzoomed layout viewport size right?

[aelias_OOO_until_Jul13, 2013/01/17 19:59:46]

I interpret "DIP" to specifically mean physical pixels divided by device scale
factor.  Any other space is not "DIP".  We need a word for this space and I
think "DIP" is unambiguous if the acronym ("density independent pixels") is
expanded.

Anyway, I've avoided this local variable entirely for now to avoid further
debate :).

+  gfx::SizeF layer_space_viewport_size = gfx::ScaleSize(dip_viewport_size, 1 / total_page_scale_factor());

[danakj, 2013/01/17 18:02:49]

which layer does layer_space refer to? is this the zoomed viewport size in
layout space? let's call it something like that if so.

[wjmaclean, 2013/01/17 19:45:52]

Should it perhaps be "layout_space_viewport_size"?

[aelias_OOO_until_Jul13, 2013/01/17 19:59:46]

OK, renamed to "layout_space_device_viewport_size".

+  return gfx::RectF(gfx::PointAtOffsetFromOrigin(zoomed_viewport_offset_), layer_space_viewport_size);
 }
 
 gfx::Vector2dF PinchZoomViewport::ApplyScroll(const gfx::Vector2dF delta) {
   gfx::Vector2dF overflow;
-  gfx::RectF pinched_bounds = Bounds() + delta;
+  gfx::RectF pinched_bounds = ZoomedViewport() + delta;
 
   if (pinched_bounds.x() < 0) {
     overflow.set_x(pinched_bounds.x());