Add use counters to determine the fate of DOMStringList

Add use counters to determine the fate of DOMStringList

BUG=460726
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=196604

[philipj_slow, 2015-06-05 18:05:48]

philipj@opera.com changed reviewers:
+ jsbell@chromium.org

[philipj_slow, 2015-06-05 18:05:49]

PTAL

[jsbell, 2015-06-05 18:12:17]

lgtm but (again) I'm not sure we'll learn much from this. Proposals to remove
DOMStringList hinge on returning a plain (or frozen...) Array, not removing the
access points.

I've let https://codereview.chromium.org/966843002 stall, but maybe we want to
pick that up again?

https://codereview.chromium.org/1162203003/diff/1/Source/modules/indexeddb/ID...
File Source/modules/indexeddb/IDBDatabase.cpp (right):

https://codereview.chromium.org/1162203003/diff/1/Source/modules/indexeddb/ID...
Source/modules/indexeddb/IDBDatabase.cpp:281:
UseCounter::count(executionContext(),
UseCounter::IDBDatabaseTransactionStoreNamesIsDOMStringList);
This won't tell us anything useful. Given that user code can't mint a
DOMStringList, this case is only practically exercised by:

db.transaction(db.objectStoreNames);

... where objectStoreNames yields a DOMStringList, so we'd already be counting
that usage, and if we change it to return an Array it would continue to work.

But no objection, since the data won't hurt.

[philipj_slow, 2015-06-05 18:19:22]

Agree that some of these may not tell us anything interesting, but I am quite
interested to know if it's Location.ancestorOrigin or IDB that's responsible for
most of the usage. If Location.ancestorOrigin is used very little, changing only
that would be nice, then IDB is all that remains and if DOMStringList.contains
usage just won't drop then IDB could define DOMStringList itself, since I doubt
any other spec will.

https://codereview.chromium.org/1162203003/diff/1/Source/modules/indexeddb/ID...
File Source/modules/indexeddb/IDBDatabase.cpp (right):

https://codereview.chromium.org/1162203003/diff/1/Source/modules/indexeddb/ID...
Source/modules/indexeddb/IDBDatabase.cpp:281:
UseCounter::count(executionContext(),
UseCounter::IDBDatabaseTransactionStoreNamesIsDOMStringList);
On 2015/06/05 18:12:17, jsbell wrote:
> This won't tell us anything useful. Given that user code can't mint a
> DOMStringList, this case is only practically exercised by:
> 
> db.transaction(db.objectStoreNames);
> 
> ... where objectStoreNames yields a DOMStringList, so we'd already be counting
> that usage, and if we change it to return an Array it would continue to work.
> 
> But no objection, since the data won't hurt.

You're right, that sounds pretty useless, so I'll remove this. If all of the
ways of getting a DOMStringList go away, so can this.

[philipj_slow, 2015-06-05 18:21:03]

Drop IDBDatabaseTransactionStoreNamesIsDOMStringList counter

[philipj_slow, 2015-06-05 18:22:46]

Will rebase this on top of https://codereview.chromium.org/1151023004/ when it
lands.

[philipj_slow, 2015-06-05 19:11:53]

rebase

[philipj_slow, 2015-06-05 19:12:00]

The CQ bit was checked by philipj@opera.com

[philipj_slow, 2015-06-05 19:12:01]

The patchset sent to the CQ was uploaded after l-g-t-m from jsbell@chromium.org
Link to the patchset: https://codereview.chromium.org/1162203003/#ps40001
(title: "rebase")

[commit-bot: I haz the power, 2015-06-05 19:12:40]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1162203003/40001

[commit-bot: I haz the power, 2015-06-05 20:41:19]

Committed patchset #3 (id:40001) as
https://src.chromium.org/viewvc/blink?view=rev&revision=196604