Fix toplevel_root parsing in trychange.py

Fix toplevel_root parsing in trychange.py

In https://codereview.chromium.org/11574007/ I attempted to make it possible to use the TRYSERVER_ROOT setting in codereview.settings. It seems like some checkouts ran into errors with it not finding the codereview.settings file when it was parsed. This is probably due to the fact that the following call chain reads the self.toplevel_root variable:
_GclStyleSettings -> GetCodeReviewSetting -> ReadRootFile
By moving _GclStyleSettings up before self.toplevel_root is set probably causes this.

This CL attempts to correct this.

BUG=none, but try job upload fails for some users.
TEST=submitting try job to locally running try server.


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=173928

[kjellander_chromium, 2012-12-19 08:29:27]

Marc-Antoine, I assume a rollback wasn't needed since noone did that. This CL
should fix the problem that Wez ran into.

Wez: Can you verify it works for you?

[M-A Ruel, 2012-12-19 13:46:12]

https://codereview.chromium.org/11571052/diff/1/trychange.py
File trychange.py (right):

https://codereview.chromium.org/11571052/diff/1/trychange.py#newcode154
trychange.py:154: This method needs to be called after self.top_level_root has
been set.
Add an assert instead?

[kjellander_chromium, 2012-12-19 16:16:15]

I updated the comment instead since I'm not sure an assert can be used in that
case.

I don't have the overview of all the different layouts of code repositories try
jobs are uploaded from, so it's hard for me to think about all the different
cases. 
Please assist me if there's any better way to achieve what I'm trying to do in
this CL.

https://codereview.chromium.org/11571052/diff/1/trychange.py
File trychange.py (right):

https://codereview.chromium.org/11571052/diff/1/trychange.py#newcode154
trychange.py:154: This method needs to be called after self.top_level_root has
been set.
On 2012/12/19 13:46:12, Marc-Antoine Ruel wrote:
> Add an assert instead?

Actually I think it's a bit confusing to say it has to be set, since there seem
to be code paths that don't require it. I changed the comment to something more
explaining instead.

[M-A Ruel, 2012-12-19 16:24:49]

lgtm

[commit-bot: I haz the power, 2012-12-19 16:26:31]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/kjellander@chromium.org/11571052/1002

[commit-bot: I haz the power, 2012-12-19 16:29:05]

Change committed as 173928