cc: Fix screen-space transform flattening in CalcDrawProps

cc: Fix screen-space transform flattening in CalcDrawProps

When computing a layer's screen-space transform, CalcDrawProps
currently flattens the target-to-screen-space transform used only if
the layer itself flattens transforms. However, a layer's
should_flatten_transform property is intended to affect flattening seen
by descendants, not flattening seen by the layer itself.

Since render surfaces act as a flattening point for their subtree, this
CL makes CalcDrawProps always flatten the full_hierarchy_matrix passed
by render surfaces to their children.

Committed: https://crrev.com/246190a883072e68382dd03b424697bca84580ce
Cr-Commit-Position: refs/heads/master@{#320144}

[ajuma, 2015-03-10 20:27:27]

ajuma@chromium.org changed reviewers:
+ enne@chromium.org, vollick@chromium.org

[ajuma, 2015-03-10 20:29:30]

I'm also working on fixing up flattening in property trees, but split this off
into a separate CL so that property tree changes aren't mixed with changes to
current behavior.

https://codereview.chromium.org/995953002/diff/1/cc/trees/layer_tree_host_com...
File cc/trees/layer_tree_host_common_unittest.cc (right):

https://codereview.chromium.org/995953002/diff/1/cc/trees/layer_tree_host_com...
cc/trees/layer_tree_host_common_unittest.cc:1546:
grand_child->screen_space_transform());
Without the change made in this CL, |grand_child|'s screen space transform would
be rotation_about_y, even though both it and |child| render into the same
surface with the same draw transform.

[enne (OOO), 2015-03-11 20:05:21]

The CQ bit was checked by enne@chromium.org

[enne (OOO), 2015-03-11 20:05:21]

lgtm

[commit-bot: I haz the power, 2015-03-11 20:05:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/995953002/20001

[commit-bot: I haz the power, 2015-03-11 20:56:14]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-03-11 20:56:41]

Patchset 2 (id:??) landed as
https://crrev.com/246190a883072e68382dd03b424697bca84580ce
Cr-Commit-Position: refs/heads/master@{#320144}