ui/gfx mojo: Don't serialize the identity matrix

ui/gfx mojo: Don't serialize the identity matrix

Identity transforms are the most common transform on the web
(most things aren't transformed) and so we shouldn't spend a bunch of time
serializing and deserializing (and validating) identity matrices.
This improves deserialization performance of CompositorFrames with a lot
of SharedQuadState or RenderPasses by between 5-15%. Where gfx::Transform
isn't used as much, this change has a negligible impact.

BUG=624459
Committed: https://crrev.com/7ca76d1cfb84ff3483540cf107bec90c99d8a90b
Cr-Commit-Position: refs/heads/master@{#411099}

[Fady Samuel, 2016-08-10 14:11:09]

fsamuel@chromium.org changed reviewers:
+ tsepez@chromium.org, vollick@chromium.org

[Fady Samuel, 2016-08-10 14:11:10]

+vollick@ for ui/gfx transform related change
+tsepez@ for security.

[Ian Vollick, 2016-08-10 15:02:34]

ui/gfx/ lgtm w/ nit.

https://codereview.chromium.org/2231013002/diff/1/ui/gfx/mojo/transform_struc...
File ui/gfx/mojo/transform_struct_traits.h (right):

https://codereview.chromium.org/2231013002/diff/1/ui/gfx/mojo/transform_struc...
ui/gfx/mojo/transform_struct_traits.h:18: static bool IsNull(const SkMatrix44&
input) { return input.isIdentity(); }
I'd prefer IsIdentity.

[Ian Vollick, 2016-08-10 15:13:57]

https://codereview.chromium.org/2231013002/diff/1/ui/gfx/mojo/transform_struc...
File ui/gfx/mojo/transform_struct_traits.h (right):

https://codereview.chromium.org/2231013002/diff/1/ui/gfx/mojo/transform_struc...
ui/gfx/mojo/transform_struct_traits.h:18: static bool IsNull(const SkMatrix44&
input) { return input.isIdentity(); }
On 2016/08/10 at 15:02:34, vollick wrote:
> I'd prefer IsIdentity.

Fady explained to me offline about how IsNull interacts with the optional.
Disregard my comment. :)

[Fady Samuel, 2016-08-10 15:19:14]

PTAL Tom!

https://codereview.chromium.org/2231013002/diff/1/ui/gfx/mojo/transform_struc...
File ui/gfx/mojo/transform_struct_traits.h (right):

https://codereview.chromium.org/2231013002/diff/1/ui/gfx/mojo/transform_struc...
ui/gfx/mojo/transform_struct_traits.h:18: static bool IsNull(const SkMatrix44&
input) { return input.isIdentity(); }
On 2016/08/10 15:13:57, vollick wrote:
> On 2016/08/10 at 15:02:34, vollick wrote:
> > I'd prefer IsIdentity.
> 
> Fady explained to me offline about how IsNull interacts with the optional.
> Disregard my comment. :)

Mojo calls IsNull to determine whether a given field should be serialized or
not.

[Tom Sepez, 2016-08-10 17:13:44]

Clever.  I don't see any security implications, so LGTM.

[Fady Samuel, 2016-08-10 17:15:27]

The CQ bit was checked by fsamuel@chromium.org

[commit-bot: I haz the power, 2016-08-10 17:16:11]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-08-10 18:41:35]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2016-08-10 18:43:28]

Description was changed from

==========
ui/gfx mojo: Don't serialize the identity matrix

Identity transforms are the most common transform on the web
(most things aren't transformed) and so we shouldn't spend a bunch of time
serializing and deserializing (and validating) identity matrices.
This improves deserialization performance of CompositorFrames with a lot
of SharedQuadState or RenderPasses by between 5-15%. Where gfx::Transform
isn't used as much, this change has a negligible impact.

BUG=624459
==========

to

==========
ui/gfx mojo: Don't serialize the identity matrix

Identity transforms are the most common transform on the web
(most things aren't transformed) and so we shouldn't spend a bunch of time
serializing and deserializing (and validating) identity matrices.
This improves deserialization performance of CompositorFrames with a lot
of SharedQuadState or RenderPasses by between 5-15%. Where gfx::Transform
isn't used as much, this change has a negligible impact.

BUG=624459

Committed: https://crrev.com/7ca76d1cfb84ff3483540cf107bec90c99d8a90b
Cr-Commit-Position: refs/heads/master@{#411099}
==========

[commit-bot: I haz the power, 2016-08-10 18:43:29]

Patchset 1 (id:??) landed as
https://crrev.com/7ca76d1cfb84ff3483540cf107bec90c99d8a90b
Cr-Commit-Position: refs/heads/master@{#411099}