Don't support active user switching in hotwording outside ChromeOS.

Don't support active user switching in hotwording outside ChromeOS.

BUG=438545
Committed: https://crrev.com/483210013ab65d17237d9c1e4e0ff0556cf9fb58
Cr-Commit-Position: refs/heads/master@{#307091}

[Anand Mistry (off Chromium), 2014-12-04 01:51:15]

amistry@chromium.org changed reviewers:
+ rlp@chromium.org

[rpetterson, 2014-12-04 18:29:26]

Two questions:

1) From the bug, it sounds like this is crashing because it's being called on
the wrong thread. How does this fix that?

2) Isn't switching based on profiles something we need on all platforms?

[Anand Mistry (off Chromium), 2014-12-04 23:58:33]

On 2014/12/04 18:29:26, rpetterson wrote:
> Two questions:
> 
> 1) From the bug, it sounds like this is crashing because it's being called on
> the wrong thread. How does this fix that?

It doesn't. Because this code is synchronous, we can't wait for the profile to
be created or hand off creation to another thread. There's also no indication
that GetActiveUserProfile() (or any other ProfileManager function) must be
called on the IO thread. I've changed the code so that it doesn't cause a
profile to be created and fails open if there are any problems.

> 2) Isn't switching based on profiles something we need on all platforms?

Nope. Turns out the mechanism for switching "active" profiles only exists on
ChromeOS. Multiple profiles on Chrome is somewhat different, and something we
already handle transparently.

[rpetterson, 2014-12-05 18:45:08]

LGTM

On 2014/12/04 23:58:33, Anand Mistry wrote:
> On 2014/12/04 18:29:26, rpetterson wrote:
> > Two questions:
> > 
> > 1) From the bug, it sounds like this is crashing because it's being called
on
> > the wrong thread. How does this fix that?
> 
> It doesn't. Because this code is synchronous, we can't wait for the profile to
> be created or hand off creation to another thread. There's also no indication
> that GetActiveUserProfile() (or any other ProfileManager function) must be
> called on the IO thread. I've changed the code so that it doesn't cause a
> profile to be created and fails open if there are any problems.
> 
> > 2) Isn't switching based on profiles something we need on all platforms?
> 
> Nope. Turns out the mechanism for switching "active" profiles only exists on
> ChromeOS. Multiple profiles on Chrome is somewhat different, and something we
> already handle transparently.

I'm actually surprised this is an issue at all. I thought most profile functions
had to be called on the UI thread which the whole reason the profile_io object
was created was in order to deal with profile functionality on the IO thread.
Maybe this is different for CrOS. But that's more of a general comment.

[Anand Mistry (off Chromium), 2014-12-05 21:08:24]

The CQ bit was checked by amistry@chromium.org

[commit-bot: I haz the power, 2014-12-05 21:09:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/752003006/20001

[commit-bot: I haz the power, 2014-12-05 22:03:06]

Committed patchset #2 (id:20001)

[commit-bot: I haz the power, 2014-12-05 22:04:39]

Patchset 2 (id:??) landed as
https://crrev.com/483210013ab65d17237d9c1e4e0ff0556cf9fb58
Cr-Commit-Position: refs/heads/master@{#307091}