Stop setting invalid value to the |tab_id| field of fileBrowserHandler API.

Stop setting invalid value to the |tab_id| field of fileBrowserHandler API.

Since the very long long ago when we have moved file manager out of tabs
to a separate app window, it didn't have any tab_id associated,
and the existing code always assigned an invalid value (-1).

This CL removes the useless code. Since the field is defined to
be optional, it doesn't change the interface of the API.

BUG=312519
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=238376

[kinaba, 2013-12-03 08:07:06]

ptal.

It's a bit odd to have a field that'll never set, but
since we are going to deprecate the API itself preferring
new Apps' file_handler, I don't think it's worth updating
the API spec precisely; it's anyway not used at all.

[hirono, 2013-12-03 08:30:42]

On 2013/12/03 08:07:06, kinaba wrote:
> ptal.
> 
> It's a bit odd to have a field that'll never set, but
> since we are going to deprecate the API itself preferring
> new Apps' file_handler, I don't think it's worth updating
> the API spec precisely; it's anyway not used at all.

lgtm! The document says the tabID is optional and unique value.
So it looks more natural rather than assigning invalid not-unique values.

[commit-bot: I haz the power, 2013-12-03 09:37:04]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/kinaba@chromium.org/101323002/1

[commit-bot: I haz the power, 2013-12-03 12:39:45]

Change committed as 238376