cc: Turn SharedQuadState into a struct-like class similar to DrawQuads.

cc: Turn SharedQuadState into a struct-like class similar to DrawQuads.

SharedQuadState was a struct previously, but required all the data to be passed
to its create() method. This makes the Create() method take no parameters, as
DrawQuads work now. And we add a SetAll() method, similar again to DrawQuad.

We remove the "id" value from ShardQuadState. This shouldn't be needed for
serialization. We can instead just use the pointers in the quads as an id
directly, and compare them against each other to see when we need to create a
new shared quad state. This is sufficient since all quads that share an
instance of SharedQuadState are appended to be adjacent in the quad list.

Covered by existing tests.

TBR=aelias
BUG=152337
Depends on: https://codereview.chromium.org/11411050

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=168960

[danakj, 2012-11-20 01:41:42]

https://codereview.chromium.org/11416088/diff/1/cc/shared_quad_state.h
File cc/shared_quad_state.h (right):

https://codereview.chromium.org/11416088/diff/1/cc/shared_quad_state.h#newcode21
cc/shared_quad_state.h:21: void SetAll(const WebKit::WebTransformationMatrix&
content_to_target_transform,
I violated 80cols here because ui::Transform will make this fit.

[aelias_OOO_until_Jul13, 2012-11-20 01:55:47]

When are you planning to create the new SharedQuadState on the receiving side? 
Keep in mind that the deserializer isn't able to mutate the quads because it
only has const pointers to them.  So you'll have to release bad pointers into
outside code and make sure to only use them for equality comparison.

Then, once you're out of the serializer, how will you know which shared quad
state to reattach them to without an ID?

[danakj, 2012-11-20 05:06:05]

On 2012/11/20 01:55:47, aelias wrote:
> When are you planning to create the new SharedQuadState on the receiving side?

> Keep in mind that the deserializer isn't able to mutate the quads because it
> only has const pointers to them.  So you'll have to release bad pointers into
> outside code and make sure to only use them for equality comparison.
> 
> Then, once you're out of the serializer, how will you know which shared quad
> state to reattach them to without an ID?

Well, I didn't think about that at the time, good point. But I think if we
always pop the first SharedQuadState off the list and use that whenever the
current quad's SQS pointer != last quad's SQS pointer, we'll get the right
results. And malicious data will at worst end up with weird rendering (we can
abort/fail if the SQS list is empty).

[danakj, 2012-11-20 05:07:33]

On 2012/11/20 05:06:05, danakj wrote:
> Well, I didn't think about that at the time, good point. But I think if we
> always pop the first SharedQuadState off the list and use that whenever the
> current quad's SQS pointer != last quad's SQS pointer, we'll get the right
> results. And malicious data will at worst end up with weird rendering (we can
> abort/fail if the SQS list is empty).

THe reason this holds is because the SQS for a set of quads is always inserted
first, then the quads for that SQS come immediately after. So the quads point at
SQS's in their list in the same order that they appear in the SQS list.

[aelias_OOO_until_Jul13, 2012-11-20 21:36:42]

lgtm.

As discussed offline, it's too brittle to rely on the ordering.  But we can
generate an ID at the last minute in the serializer and never expose it to CC.

[commit-bot: I haz the power, 2012-11-20 23:09:53]

No LGTM from a valid reviewer yet. Only full committers are accepted.
Even if an LGTM may have been provided, it was from a non-committer or
a lowly provisional committer, _not_ a full super star committer.
See http://www.chromium.org/getting-involved/become-a-committer
Note that this has nothing to do with OWNERS files.

[commit-bot: I haz the power, 2012-11-20 23:11:09]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/danakj@chromium.org/11416088/19

[commit-bot: I haz the power, 2012-11-20 23:29:00]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/danakj@chromium.org/11416088/3019

[commit-bot: I haz the power, 2012-11-21 04:02:26]

Change committed as 168960