Add base::BindToTaskRunner and BindToCurrentThread

Add base::BindToTaskRunner and BindToCurrentThread

It is useful to be able to bind a callback that will run on a given
TaskRunner. This is partially covered by media::BindToCurrentLoop,
but it makes more sense for this functionality to be in base.

For now I have marked media::BindToCurrentLoop as deprecated, and
updated it to just wrap base::BindToCurrentThread.

BUG=
TEST= base_unittests

[kmackay, 2015-12-29 22:13:40]

kmackay@chromium.org changed reviewers:
+ maclellant@chromium.org, thestig@chromium.org, tzik@chromium.org,
xhwang@chromium.org

[Lei Zhang, 2015-12-29 22:19:50]

Do you have other non-media/ users in mind? Unless there is strong demand for
this elsewhere, it should probably stay in media/.

[kmackay, 2015-12-29 22:25:00]

On 2015/12/29 22:19:50, Lei Zhang wrote:
> Do you have other non-media/ users in mind? Unless there is strong demand for
> this elsewhere, it should probably stay in media/.

We are using it a fair amount in chromecast as well. I'm ok with just leaving
media/bind_to_current_loop.h as-is and putting this code in chromecast/base
though.

[Lei Zhang, 2015-12-29 22:36:52]

On 2015/12/29 22:25:00, kmackay wrote:
> On 2015/12/29 22:19:50, Lei Zhang wrote:
> > Do you have other non-media/ users in mind? Unless there is strong demand
for
> > this elsewhere, it should probably stay in media/.
> 
> We are using it a fair amount in chromecast as well. I'm ok with just leaving
> media/bind_to_current_loop.h as-is and putting this code in chromecast/base
> though.

Sure. If we find ourselves with many copies in the future, we'll consolidate it
to base/.

[kmackay, 2015-12-29 22:47:40]

Description was changed from

==========
Add base::BindToTaskRunner and BindToCurrentThread

It is useful to be able to bind a callback that will run on a given
TaskRunner. This is partially covered by media::BindToCurrentLoop,
but it makes more sense for this functionality to be in base.

For now I have marked media::BindToCurrentLoop as deprecated, and
updated it to just wrap base::BindToCurrentThread.

BUG=
TEST= base_unittests
==========

to

==========
Add base::BindToTaskRunner and BindToCurrentThread

It is useful to be able to bind a callback that will run on a given
TaskRunner. This is partially covered by media::BindToCurrentLoop,
but it makes more sense for this functionality to be in base.

For now I have marked media::BindToCurrentLoop as deprecated, and
updated it to just wrap base::BindToCurrentThread.

BUG=
TEST= base_unittests
==========

[xhwang, 2016-01-04 19:05:21]

xhwang@chromium.org changed reviewers:
+ danakj@chromium.org

[xhwang, 2016-01-04 19:05:21]

I think there are actually more people wanting this. The fact that this isn't
widely used is probably because it's not in base/....

Here's the bug to track this:

https://code.google.com/p/chromium/issues/detail?id=432381

One issue is that even though the callback is bound to a given task runner, it's
still possible that that callback can be destroyed on a different task runner,
which could cause trouble in some cases. There's an attempt to fix this, but
it's not finished:

https://chromiumcodereview.appspot.com/1082113004/

[danakj, 2016-01-04 20:01:48]

On 2016/01/04 19:05:21, xhwang wrote:
> I think there are actually more people wanting this. The fact that this isn't
> widely used is probably because it's not in base/....
> 
> Here's the bug to track this:
> 
> https://code.google.com/p/chromium/issues/detail?id=432381
> 
> One issue is that even though the callback is bound to a given task runner,
it's
> still possible that that callback can be destroyed on a different task runner,
> which could cause trouble in some cases. There's an attempt to fix this, but
> it's not finished:
> 
> https://chromiumcodereview.appspot.com/1082113004/

Ya... as from there we found no good compromise on making the tool not leaky and
I didn't want to add a leaky thing to base. Nothing has changed on either of
those afaik.