Implement RefCountedCopyable<T>.

Implement RefCountedCopyable<T>.

Currently, subclasses of RefCounted<T> must explicitly handwrite their
copy constructors because RefCounted<T> has a deleted copy constructor.
This is tedious for subclasses that have a lot of members (e.g.
StyleRareNonInheritedData).

RefCountedCopyable<T> is a base class for ref-counted classes that
want to be copyable as well. RefCountedCopyable<T> implements a
protected copy constructor that resets the ref count to zero. Because
the copy constructor is protected, the compiler is able to generate a
default copy constructor for subclasses.

This patch moves StyleBoxData to RefCountedCopyable as an example.

BUG=628043
Review-Url: https://codereview.chromium.org/2781313004
Cr-Commit-Position: refs/heads/master@{#461656}
Committed: https://chromium.googlesource.com/chromium/src/+/de33c94cc211c5ee1994ce3fa0d43abc355a4e9c

[shend, 2017-03-31 05:20:46]

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

[commit-bot: I haz the power, 2017-03-31 05:21:06]

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

[shend, 2017-03-31 05:22:36]

shend@chromium.org changed reviewers:
+ alancutter@chromium.org

[shend, 2017-03-31 05:22:36]

Hi Alan, PTAL :)

[commit-bot: I haz the power, 2017-03-31 08:13:38]

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

[commit-bot: I haz the power, 2017-03-31 08:13:38]

Dry run: This issue passed the CQ dry run.

[alancutter (OOO until 2018), 2017-04-03 12:07:45]

You'll need platform OWNERs review as well.

https://codereview.chromium.org/2781313004/diff/1/third_party/WebKit/Source/p...
File third_party/WebKit/Source/platform/wtf/RefCounted.h (right):

https://codereview.chromium.org/2781313004/diff/1/third_party/WebKit/Source/p...
third_party/WebKit/Source/platform/wtf/RefCounted.h:169: // compiler-generated
copy constructor.
This wording is a bit too fancy. For speed of reading the point should be the
first thing conveyed. "Allows subclasses to use their default copy constructor,
...".

[alancutter (OOO until 2018), 2017-04-03 12:07:50]

lgtm

[shend, 2017-04-03 22:23:50]

shend@chromium.org changed reviewers:
+ haraken@chromium.org

[shend, 2017-04-03 22:23:50]

Hi haraken, PTAL for platform/ :)

[haraken, 2017-04-04 05:36:34]

LGTM!

[shend, 2017-04-04 06:29:03]

The CQ bit was checked by shend@chromium.org

[shend, 2017-04-04 06:29:04]

The patchset sent to the CQ was uploaded after l-g-t-m from
alancutter@chromium.org
Link to the patchset: https://codereview.chromium.org/2781313004/#ps20001
(title: "Address comments")

[commit-bot: I haz the power, 2017-04-04 06:29:21]

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, 2017-04-04 08:02:32]

CQ is committing da patch.

Bot data: {"patchset_id": 20001, "attempt_start_ts": 1491287343918800,
"parent_rev": "65d1e47c314fee42363b652ddbccf0dbea9a73c7", "commit_rev":
"de33c94cc211c5ee1994ce3fa0d43abc355a4e9c"}

[commit-bot: I haz the power, 2017-04-04 08:03:19]

Description was changed from

==========
Implement RefCountedCopyable<T>.

Currently, subclasses of RefCounted<T> must explicitly handwrite their
copy constructors because RefCounted<T> has a deleted copy constructor.
This is tedious for subclasses that have a lot of members (e.g.
StyleRareNonInheritedData).

RefCountedCopyable<T> is a base class for ref-counted classes that
want to be copyable as well. RefCountedCopyable<T> implements a
protected copy constructor that resets the ref count to zero. Because
the copy constructor is protected, the compiler is able to generate a
default copy constructor for subclasses.

This patch moves StyleBoxData to RefCountedCopyable as an example.

BUG=628043
==========

to

==========
Implement RefCountedCopyable<T>.

Currently, subclasses of RefCounted<T> must explicitly handwrite their
copy constructors because RefCounted<T> has a deleted copy constructor.
This is tedious for subclasses that have a lot of members (e.g.
StyleRareNonInheritedData).

RefCountedCopyable<T> is a base class for ref-counted classes that
want to be copyable as well. RefCountedCopyable<T> implements a
protected copy constructor that resets the ref count to zero. Because
the copy constructor is protected, the compiler is able to generate a
default copy constructor for subclasses.

This patch moves StyleBoxData to RefCountedCopyable as an example.

BUG=628043

Review-Url: https://codereview.chromium.org/2781313004
Cr-Commit-Position: refs/heads/master@{#461656}
Committed:
https://chromium.googlesource.com/chromium/src/+/de33c94cc211c5ee1994ce3fa0d4...
==========

[commit-bot: I haz the power, 2017-04-04 08:03:22]

Committed patchset #2 (id:20001) as
https://chromium.googlesource.com/chromium/src/+/de33c94cc211c5ee1994ce3fa0d4...