cc: Plumbing for storing property trees

cc: Plumbing for storing property trees

In order to commit property trees to the compositor thread, they need to
be stored on the LayerTreeHost/LayerTreeImpl.  This change adds plumbing
so that the PropertyTree computation is not entirely internal to CDP.

BUG=386793
Committed: https://crrev.com/c3011475c142d226e28bd4256a12deeda139f783
Cr-Commit-Position: refs/heads/master@{#324331}

[enne (OOO), 2015-04-07 23:57:10]

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

[Ian Vollick, 2015-04-08 02:45:56]

lgtm.

https://codereview.chromium.org/1062403002/diff/1/cc/trees/property_tree.h
File cc/trees/property_tree.h (right):

https://codereview.chromium.org/1062403002/diff/1/cc/trees/property_tree.h#ne...
cc/trees/property_tree.h:200: class CC_EXPORT PropertyTrees final {
So much better!

[enne (OOO), 2015-04-08 16:09:49]

The CQ bit was checked by enne@chromium.org

[commit-bot: I haz the power, 2015-04-08 16:10:13]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1062403002/1

[commit-bot: I haz the power, 2015-04-08 16:46:58]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-04-08 16:47:00]

Try jobs failed on following builders:
  android_arm64_dbg_recipe on tryserver.chromium.linux (JOB_FAILED,
http://build.chromium.org/p/tryserver.chromium.linux/builders/android_arm64_d...)

[enne (OOO), 2015-04-08 22:09:14]

The CQ bit was checked by enne@chromium.org

[enne (OOO), 2015-04-08 22:09:14]

The patchset sent to the CQ was uploaded after l-g-t-m from vollick@chromium.org
Link to the patchset: https://codereview.chromium.org/1062403002/#ps20001
(title: "Fix perf test compile failure")

[commit-bot: I haz the power, 2015-04-08 22:12:14]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1062403002/20001

[commit-bot: I haz the power, 2015-04-09 01:27:37]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-04-09 01:28:25]

Patchset 2 (id:??) landed as
https://crrev.com/c3011475c142d226e28bd4256a12deeda139f783
Cr-Commit-Position: refs/heads/master@{#324331}