[MediaStream API] Allow empty MediaStreams

[MediaStream API] Allow empty MediaStreams
The spec is a bit unclear ecactly what should happen with newly created MediaStreams
that doesn't have any tracks. The current implementation is too strict and the spec
is being worked upon to be clearer. In the meantime this patch doesn't set eneded to
true in the constructor.

R=abarth@chromium.org,li.yin@intel.com
BUG=229350
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=147925

[abarth-chromium, 2013-04-08 16:44:30]

lgtm

[Li Yin, 2013-04-09 01:19:27]

On 2013/04/08 16:44:30, abarth wrote:
> lgtm

Yes, the spec has no introduction about empty stream. If we changed
implementation like this, my concern is that it has different behavior with when
all tracks have been removed from MediaStream.
That is to say, when MediaStream is created with an empty stream, the ended
status return false. but when all tracks has been removed from no empty streams,
it returns true.
I don't know if it is confused for web developers.

[Tommy Widenflycht, 2013-04-09 07:40:46]

Yeah, it's not completely symmetrical but a bug has been filed against the spec
to clarify this.

On 2013/04/09 01:19:27, Li Yin wrote:
> On 2013/04/08 16:44:30, abarth wrote:
> > lgtm
> 
> Yes, the spec has no introduction about empty stream. If we changed
> implementation like this, my concern is that it has different behavior with
when
> all tracks have been removed from MediaStream.
> That is to say, when MediaStream is created with an empty stream, the ended
> status return false. but when all tracks has been removed from no empty
streams,
> it returns true.
> I don't know if it is confused for web developers.

[Tommy Widenflycht, 2013-04-09 13:16:03]

Committed patchset #1 manually as r147925 (presubmit successful).