Prevent the in-process PDF plugin re-entering into JS during blink layout

Prevent the in-process PDF plugin re-entering into JS during blink layout

Layout changes trigger view changes which get sent to the plugin. With the
in process plugin (PDF), the plugin is notified synchronously of the view
change. It then might execute scripts synchronously in the plugin but
scripts are not meant to be executed during layout changes. This change
runs the scripts asynchronously. I tested print preview to ensure that it
still works correctly.

Note that once we remove in-process plugins this won't be an issue because
view changes happen asynchronously out of process (besides the fact that
synchronous script execution is limited to private plugins).

BUG=351636
Committed: https://crrev.com/8410df4f4a7c54f2d669b6cc717ec9a09b76ad79
Cr-Commit-Position: refs/heads/master@{#293256}

[raymes, 2014-09-03 04:19:05]

raymes@chromium.org changed reviewers:
+ thestig@chromium.org

[Lei Zhang, 2014-09-03 22:22:20]

The CQ bit was checked by thestig@chromium.org

[Lei Zhang, 2014-09-03 22:22:20]

lgtm

[commit-bot: I haz the power, 2014-09-03 23:24:08]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/raymes@chromium.org/530363002/1

[commit-bot: I haz the power, 2014-09-04 02:23:06]

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

[commit-bot: I haz the power, 2014-09-04 02:23:06]

Try jobs failed on following builders:
  android_clang_dbg_recipe on tryserver.chromium.linux
(http://build.chromium.org/p/tryserver.chromium.linux/builders/android_clang_d...)

[raymes, 2014-09-04 03:36:16]

The CQ bit was checked by raymes@chromium.org

[commit-bot: I haz the power, 2014-09-04 03:37:05]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/raymes@chromium.org/530363002/1

[commit-bot: I haz the power, 2014-09-04 04:29:08]

Committed patchset #1 (id:1) as 98cadacd91ab272e7a95304bfe3ec31ad3a554fb

[commit-bot: I haz the power, 2014-09-10 03:29:41]

Patchset 1 (id:??) landed as
https://crrev.com/8410df4f4a7c54f2d669b6cc717ec9a09b76ad79
Cr-Commit-Position: refs/heads/master@{#293256}