Allow external protocol handlers to open in Windows 8.

Allow external protocol handlers to open in Windows 8.

This was broken due to changes to the Windows 8 APIs around default
handlers. Chrome checks if it is the default handler for the protocol
before launching any external program. Prior to this change the check
on Windows 8 would always return success. This change makes it return
UNKOWN instead.

BUG=116452
TEST=Tested external handlers work on Win 7 and Win 8. Checked register
     protocol handler still works on Win 8.


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=129557

[grt (UTC plus 2), 2012-03-27 20:21:07]

Code LGTM, although I don't have any specific Win8 knowledge to judge whether or
not this is the right approach overall.

[benwells, 2012-03-28 01:18:19]

On 2012/03/27 20:21:07, grt wrote:
> Code LGTM, although I don't have any specific Win8 knowledge to judge whether
or
> not this is the right approach overall.

The change with Win8 is that Microsoft wants the OS to provide all UI to do with
default programs. One effect of this is that the
ApplicationAssociationRegistration.QueryIsDefault function always returns
success now, regardless of the actual default.

This has broken opening external applications for schemes like steam:// or
magnet://. This change only fixes that bug and doesn't change any other
behaviour, in particular the registerProtocolHandler system is still working the
same on Win8.

More changes are needed in the area, but I think this can go in as is before
tackling the other changes.

[grt (UTC plus 2), 2012-03-28 02:12:12]

Thanks for the explanation.  Still LGTM!

[cpu_(ooo_6.6-7.5), 2012-03-28 22:18:52]

lgtm

[commit-bot: I haz the power, 2012-03-28 22:50:58]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/benwells@chromium.org/9863026/1

[commit-bot: I haz the power, 2012-03-29 01:59:46]

Change committed as 129557