Block scripting in plugin teardown during Document unload.

Block scripting in plugin teardown during Document unload.

Eventually, this should eliminate the need to run a nested message
loop in some situations when plugins are destroyed...

BUG=498088
Committed: https://crrev.com/16be73c3c077f4d44e094fcebf0b9583a4accb26
Cr-Commit-Position: refs/heads/master@{#334047}

[dcheng, 2015-06-10 01:18:28]

dcheng@chromium.org changed reviewers:
+ bbudge@chromium.org

[dcheng, 2015-06-10 01:18:28]

Blink-side patch is at https://codereview.chromium.org/1170413003

Note that the scope of this patch is very narrow. Script execution is only
blocked if both of the following conditions are true:
- We are in the middle of blowing away the Document, either because the frame is
being detached or navigated.
- The plugin being destroyed attempts to execute script.

The eventual goal is to remove the need to dispatch a sync IPC to shutdown
plugins in the cases where Blink ignores scripting attempts, eliminating the
nested message loop.

Yay. Flash.

[dcheng, 2015-06-10 01:18:41]

(CC piman@ as an FYI)

[piman, 2015-06-10 02:27:07]

piman@chromium.org changed reviewers:
+ piman@chromium.org

[piman, 2015-06-10 02:27:08]

FYI, for scripting back into the document, there's also everything in
content/renderer/pepper/ppb_var_deprecated_impl.cc

[dcheng, 2015-06-10 03:10:12]

On 2015/06/10 at 02:27:08, piman wrote:
> FYI, for scripting back into the document, there's also everything in
content/renderer/pepper/ppb_var_deprecated_impl.cc

Blah, I was under the impression you couldn't do a whole lot with object
PP_Vars. I'll take a look...

[dcheng, 2015-06-10 03:24:25]

OK, updated this to deal with the legacy NPAPI compatibility stuff in PPAPI too.

[dcheng, 2015-06-11 19:01:35]

Ping =)

[bbudge, 2015-06-11 20:03:07]

lgtm

[dcheng, 2015-06-11 20:27:28]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2015-06-11 20:29:23]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1172143004/20001

[commit-bot: I haz the power, 2015-06-11 22:02:49]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-06-11 22:05:03]

Patchset 2 (id:??) landed as
https://crrev.com/16be73c3c077f4d44e094fcebf0b9583a4accb26
Cr-Commit-Position: refs/heads/master@{#334047}