Add scoped_ptr-safe base::Value to Dictionary/List conversion functions.

Add scoped_ptr-safe base::Value to Dictionary/List conversion functions.

This change adds two static From() functions to the DictionaryValue and
ListValue classes which take a scoped_ptr to a Value and either convert
it to a scoped_ptr to a DictionaryValue or ListValue, or return nullptr.
These are intended to replace the existing pattern,

  make_scoped_ptr(static_cast<base::DictionaryValue*>(value.release()))

with the shorter and safer alternative,

  base::DictionaryValue::From(value.Pass())

Instances of this pattern in //extensions have been converted as
examples.

Committed: https://crrev.com/259c0a3f44bdd8130c5d835e9f596624a079fbd1
Cr-Commit-Position: refs/heads/master@{#348294}

[Reilly Grant (use Gerrit), 2015-09-08 19:46:59]

reillyg@chromium.org changed reviewers:
+ thestig@chromium.org

[Reilly Grant (use Gerrit), 2015-09-08 19:46:59]

What do you think of these new wrappers?

[Lei Zhang, 2015-09-08 20:25:55]

thestig@chromium.org changed reviewers:
+ estade@chromium.org

[Lei Zhang, 2015-09-08 20:25:55]

Or maybe as:
static scoped_ptr<DictionaryValue> DictionaryValue::CreateFrom(scoped_ptr<Value>
value) ?

+estade for his opinion

[Reilly Grant (use Gerrit), 2015-09-08 20:33:10]

On 2015/09/08 20:25:55, Lei Zhang wrote:
> Or maybe as:
> static scoped_ptr<DictionaryValue>
DictionaryValue::CreateFrom(scoped_ptr<Value>
> value) ?
> 
> +estade for his opinion

CreateFrom implies to me that it would be a deep copy. I'd stick with
DictionaryValue::From if we want to make this a static member.

[Evan Stade, 2015-09-08 21:12:27]

On 2015/09/08 20:33:10, Reilly Grant wrote:
> On 2015/09/08 20:25:55, Lei Zhang wrote:
> > Or maybe as:
> > static scoped_ptr<DictionaryValue>
> DictionaryValue::CreateFrom(scoped_ptr<Value>
> > value) ?
> > 
> > +estade for his opinion
> 
> CreateFrom implies to me that it would be a deep copy. I'd stick with
> DictionaryValue::From if we want to make this a static member.

agreed, "create" sounds like a copy instead of just a cast. ValueAsDictionary or
CastToDictionary both seem fine to me.

[Reilly Grant (use Gerrit), 2015-09-10 19:38:52]

On 2015/09/08 21:12:27, Evan Stade wrote:
> On 2015/09/08 20:33:10, Reilly Grant wrote:
> > On 2015/09/08 20:25:55, Lei Zhang wrote:
> > > Or maybe as:
> > > static scoped_ptr<DictionaryValue>
> > DictionaryValue::CreateFrom(scoped_ptr<Value>
> > > value) ?
> > > 
> > > +estade for his opinion
> > 
> > CreateFrom implies to me that it would be a deep copy. I'd stick with
> > DictionaryValue::From if we want to make this a static member.
> 
> agreed, "create" sounds like a copy instead of just a cast. ValueAsDictionary
or
> CastToDictionary both seem fine to me.

So, these new functions are good as they stand or thestig, would you like them
converted to static members?

[Lei Zhang, 2015-09-10 21:01:22]

On 2015/09/10 19:38:52, Reilly Grant wrote:
> So, these new functions are good as they stand or thestig, would you like them
> converted to static members?

static members please

[Reilly Grant (use Gerrit), 2015-09-10 22:16:05]

On 2015/09/10 21:01:22, Lei Zhang wrote:
> On 2015/09/10 19:38:52, Reilly Grant wrote:
> > So, these new functions are good as they stand or thestig, would you like
them
> > converted to static members?
> 
> static members please

Done.

[Lei Zhang, 2015-09-10 22:21:18]

lgtm

[Reilly Grant (use Gerrit), 2015-09-10 23:04:47]

The CQ bit was checked by reillyg@chromium.org

[commit-bot: I haz the power, 2015-09-10 23:05:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1308013005/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1308013005/20001

[commit-bot: I haz the power, 2015-09-11 00:25:59]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2015-09-11 00:26:47]

Patchset 2 (id:??) landed as
https://crrev.com/259c0a3f44bdd8130c5d835e9f596624a079fbd1
Cr-Commit-Position: refs/heads/master@{#348294}

[commit-bot: I haz the power, 2015-09-23 12:16:52]

Patchset 2 (id:??) landed as
https://crrev.com/259c0a3f44bdd8130c5d835e9f596624a079fbd1
Cr-Commit-Position: refs/heads/master@{#348294}