Add CHECKs in WindowProxy initialization/detach to enforce invariants

Add CHECKs in WindowProxy initialization/detach to enforce invariants

This changes the DCHECKs in disposeContext() to CHECKs and adds a new
CHECK in setGlobal(). This should help catch situations where:
- an already initialized global proxy object is overwritten but not
  reinitialized: this can happen during WebFrame::swap() if the
  embedder tries to access other script contexts, leading to out of sync
  state.
- the global proxy object that WindowProxy retains and the global proxy
  object retained by the v8::Context differ, also leading to out of sync
  state.

BUG=700077
Review-Url: https://codereview.chromium.org/2741923002
Cr-Commit-Position: refs/heads/master@{#456016}
Committed: https://chromium.googlesource.com/chromium/src/+/e8b77cc6ed024fb219d6de46378bf18eb05ae7f6

[dcheng, 2017-03-10 05:16:05]

The CQ bit was checked by dcheng@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2017-03-10 05:16:19]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[dcheng, 2017-03-10 05:18:23]

dcheng@chromium.org changed reviewers:
+ haraken@chromium.org, yukishiino@chromium.org

[dcheng, 2017-03-10 05:18:24]

WDYT? All the previous crashes were from instances of this bug, so this should
help us determine if there are any more like this.

If there are additional crashes, I have a followup patch prepared to help
diagnose any other issues.

[Yuki, 2017-03-10 06:25:01]

LGTM.

[commit-bot: I haz the power, 2017-03-10 06:42:39]

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

[commit-bot: I haz the power, 2017-03-10 06:42:39]

Dry run: This issue passed the CQ dry run.

[dcheng, 2017-03-10 07:20:10]

The CQ bit was checked by dcheng@chromium.org

[commit-bot: I haz the power, 2017-03-10 07:20:18]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-03-10 07:24:50]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1489130410186030, "parent_rev":
"7e9da2599e7fe5c5dcea7439851066905ce6932b", "commit_rev":
"e8b77cc6ed024fb219d6de46378bf18eb05ae7f6"}

[commit-bot: I haz the power, 2017-03-10 07:25:25]

Description was changed from

==========
Add CHECKs in WindowProxy initialization/detach to enforce invariants

This changes the DCHECKs in disposeContext() to CHECKs and adds a new
CHECK in setGlobal(). This should help catch situations where:
- an already initialized global proxy object is overwritten but not
  reinitialized: this can happen during WebFrame::swap() if the
  embedder tries to access other script contexts, leading to out of sync
  state.
- the global proxy object that WindowProxy retains and the global proxy
  object retained by the v8::Context differ, also leading to out of sync
  state.

BUG=700077
==========

to

==========
Add CHECKs in WindowProxy initialization/detach to enforce invariants

This changes the DCHECKs in disposeContext() to CHECKs and adds a new
CHECK in setGlobal(). This should help catch situations where:
- an already initialized global proxy object is overwritten but not
  reinitialized: this can happen during WebFrame::swap() if the
  embedder tries to access other script contexts, leading to out of sync
  state.
- the global proxy object that WindowProxy retains and the global proxy
  object retained by the v8::Context differ, also leading to out of sync
  state.

BUG=700077

Review-Url: https://codereview.chromium.org/2741923002
Cr-Commit-Position: refs/heads/master@{#456016}
Committed:
https://chromium.googlesource.com/chromium/src/+/e8b77cc6ed024fb219d6de46378b...
==========

[commit-bot: I haz the power, 2017-03-10 07:25:26]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/e8b77cc6ed024fb219d6de46378b...

[haraken, 2017-03-10 09:13:39]

LGTM