Turn IDBTransaction into the ContextLifecycleObserver it needs to be.

Turn IDBTransaction into the ContextLifecycleObserver it needs to be.

Revert r453574's switch to using ContextClient for IDBTransaction,
going back to ContextLifecycleObserver. This is needed in order for
IDBTransaction's debug checks upon destruction to be able to safely access
the ExecutionContext.

While ContextClient keeps a weak reference to its ExecutionContext,
accessing it from a destructor assumes that weak processing for the
ContextClient will already have run (and cleared out the ExecutionContext
weak reference, if needs be.) This assumes that weak processing will
always run, which it won't if the ContextClient and ExecutionContext are
determined to be garbage during the same GC.

Update ContextLifecycleObserver comments to mention this subtle detail.

R=jsbell,haraken
BUG=699819
Review-Url: https://codereview.chromium.org/2742393002
Cr-Commit-Position: refs/heads/master@{#456432}
Committed: https://chromium.googlesource.com/chromium/src/+/5dec7437ab22a52aa3dcab8e3415142b6db89040

[sof, 2017-03-13 15:21:02]

The CQ bit was checked by sigbjornf@opera.com to run a CQ dry run

[commit-bot: I haz the power, 2017-03-13 15:21:22]

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

[sof, 2017-03-13 15:21:46]

sigbjornf@opera.com changed reviewers:
+ haraken@chromium.org, jsbell@chromium.org

[sof, 2017-03-13 15:21:47]

please take a look.

[jsbell, 2017-03-13 16:02:33]

lgtm

[haraken, 2017-03-13 16:06:04]

LGTM

[commit-bot: I haz the power, 2017-03-13 17:17:07]

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

[commit-bot: I haz the power, 2017-03-13 17:17:08]

Dry run: This issue passed the CQ dry run.

[sof, 2017-03-13 18:11:24]

Description was changed from

==========
Turn IDBTransaction into the ContextLifecycleObserver it needs to be.

Revert r453574's switch to using ContextClient for IDBTransaction,
going back to ContextLifecycleObserver. This is needed in order for
IDBTransaction's debug checks upon destruction to be able to safely access
the ExecutionContext.

While ContextClient keeps a weak reference to its ExecutionContext,
accessing it from a destructor assumes that weak processing for the
ContextClient will already have run (and cleared out the ExecutionContext
weak reference, if needs be.) This assumes that weak processing will
always run, which it won't if the ContextClient and ExecutionContext are
determined to be garbage during the same GC.

Update ContextLifecycleObserver comments to mention this subtle detail.

R=
BUG=699819
==========

to

==========
Turn IDBTransaction into the ContextLifecycleObserver it needs to be.

Revert r453574's switch to using ContextClient for IDBTransaction,
going back to ContextLifecycleObserver. This is needed in order for
IDBTransaction's debug checks upon destruction to be able to safely access
the ExecutionContext.

While ContextClient keeps a weak reference to its ExecutionContext,
accessing it from a destructor assumes that weak processing for the
ContextClient will already have run (and cleared out the ExecutionContext
weak reference, if needs be.) This assumes that weak processing will
always run, which it won't if the ContextClient and ExecutionContext are
determined to be garbage during the same GC.

Update ContextLifecycleObserver comments to mention this subtle detail.

R=jsbell,haraken
BUG=699819
==========

[sof, 2017-03-13 18:11:28]

The CQ bit was checked by sigbjornf@opera.com

[commit-bot: I haz the power, 2017-03-13 18:12:03]

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, 2017-03-13 18:19:32]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1489428688653640, "parent_rev":
"e0d90f791044ede7818fbc03ce516711f463d997", "commit_rev":
"5dec7437ab22a52aa3dcab8e3415142b6db89040"}

[commit-bot: I haz the power, 2017-03-13 18:20:52]

Description was changed from

==========
Turn IDBTransaction into the ContextLifecycleObserver it needs to be.

Revert r453574's switch to using ContextClient for IDBTransaction,
going back to ContextLifecycleObserver. This is needed in order for
IDBTransaction's debug checks upon destruction to be able to safely access
the ExecutionContext.

While ContextClient keeps a weak reference to its ExecutionContext,
accessing it from a destructor assumes that weak processing for the
ContextClient will already have run (and cleared out the ExecutionContext
weak reference, if needs be.) This assumes that weak processing will
always run, which it won't if the ContextClient and ExecutionContext are
determined to be garbage during the same GC.

Update ContextLifecycleObserver comments to mention this subtle detail.

R=jsbell,haraken
BUG=699819
==========

to

==========
Turn IDBTransaction into the ContextLifecycleObserver it needs to be.

Revert r453574's switch to using ContextClient for IDBTransaction,
going back to ContextLifecycleObserver. This is needed in order for
IDBTransaction's debug checks upon destruction to be able to safely access
the ExecutionContext.

While ContextClient keeps a weak reference to its ExecutionContext,
accessing it from a destructor assumes that weak processing for the
ContextClient will already have run (and cleared out the ExecutionContext
weak reference, if needs be.) This assumes that weak processing will
always run, which it won't if the ContextClient and ExecutionContext are
determined to be garbage during the same GC.

Update ContextLifecycleObserver comments to mention this subtle detail.

R=jsbell,haraken
BUG=699819

Review-Url: https://codereview.chromium.org/2742393002
Cr-Commit-Position: refs/heads/master@{#456432}
Committed:
https://chromium.googlesource.com/chromium/src/+/5dec7437ab22a52aa3dcab8e3415...
==========

[commit-bot: I haz the power, 2017-03-13 18:20:53]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/5dec7437ab22a52aa3dcab8e3415...