cc: Refactored UpdateTilingsToCurrentRasterSource a bit; added comments

cc: Refactored UpdateTilingsToCurrentRasterSource a bit; added comments

This patch is just a small refactor with a few more comments explaining
what this function is meant to do. I've been confused in the past when
trying to remember what this function does, so hopefully this helps...

R=danakj, enne

Committed: https://crrev.com/1fa2084955406d18b9931f65bdaa4f370f31c20a
Cr-Commit-Position: refs/heads/master@{#318931}

[vmpstr, 2015-03-03 01:25:00]

Please take a look.

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
File cc/resources/picture_layer_tiling_set.cc (right):

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
cc/resources/picture_layer_tiling_set.cc:112: // If |twin_twin_set| is present,
then |this| is active and |tiling| is not
Is this actually true? If the pending_twin_set doesn't have a high res, then
we'd be resetting all others to NON_IDEAL, which means we could end up with no
high res tiling. Or am I missing something?

[vmpstr, 2015-03-03 01:27:22]

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
File cc/resources/picture_layer_tiling_set.cc (right):

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
cc/resources/picture_layer_tiling_set.cc:112: // If |twin_twin_set| is present,
then |this| is active and |tiling| is not
On 2015/03/03 01:25:00, vmpstr wrote:
> Is this actually true? If the pending_twin_set doesn't have a high res, then
> we'd be resetting all others to NON_IDEAL, which means we could end up with no
> high res tiling. Or am I missing something?

Oh nevermind, I misunderstood that we _would_ create a high res on the pending
before pushing to active, it's just it might not be there when committing.

[danakj, 2015-03-03 18:17:00]

LGTM

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
File cc/resources/picture_layer_tiling_set.cc (right):

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
cc/resources/picture_layer_tiling_set.cc:112: // If |twin_twin_set| is present,
then |this| is active and |tiling| is not
twin_twin_set? :)

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
File cc/resources/picture_layer_tiling_set.h (right):

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
cc/resources/picture_layer_tiling_set.h:62: // either the pending tree or on the
sync tree (in cases of one tree),
"is called on the sync tree" i think. the pending tree can be the sync tree so
saying "or" seems weird

[vmpstr, 2015-03-03 19:00:31]

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
File cc/resources/picture_layer_tiling_set.cc (right):

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
cc/resources/picture_layer_tiling_set.cc:112: // If |twin_twin_set| is present,
then |this| is active and |tiling| is not
On 2015/03/03 18:17:00, danakj wrote:
> twin_twin_set? :)

Oops. Changed.

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
File cc/resources/picture_layer_tiling_set.h (right):

https://codereview.chromium.org/973713002/diff/1/cc/resources/picture_layer_t...
cc/resources/picture_layer_tiling_set.h:62: // either the pending tree or on the
sync tree (in cases of one tree),
On 2015/03/03 18:17:00, danakj wrote:
> "is called on the sync tree" i think. the pending tree can be the sync tree so
> saying "or" seems weird

Done.

[vmpstr, 2015-03-03 19:00:35]

The CQ bit was checked by vmpstr@chromium.org

[vmpstr, 2015-03-03 19:00:36]

The patchset sent to the CQ was uploaded after l-g-t-m from danakj@chromium.org
Link to the patchset: https://codereview.chromium.org/973713002/#ps20001 (title:
"update")

[commit-bot: I haz the power, 2015-03-03 19:01:38]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/973713002/20001

[commit-bot: I haz the power, 2015-03-03 19:55:41]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-03-03 19:56:13]

Patchset 2 (id:??) landed as
https://crrev.com/1fa2084955406d18b9931f65bdaa4f370f31c20a
Cr-Commit-Position: refs/heads/master@{#318931}