ui/base/models: Reverse the DCHECKs of index.

ui/base/models: Reverse the DCHECKs of index.

The way it's written until now is counter-intuitive. This makes it intuitive.

1 - To make sure an int index is in the array range when we are adding we should check for:
index >= 0 && index <= child_count().

So use DCHECK_GE for '>=' and DCHECK_LE for '<=' respectively.

2 - To make sure an int index is in the array range when we are retrieving it from vector we should check for:
index >= 0 && index < child_count().

So use DCHECK_GE for '>=' and DCHECK_LT for '<' respectively.

BUG=None
TEST=app_unittests --gtest_filter=TreeNodeModelTest.*

R=sky@chromium.org

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=87716

[tfarina, 2011-06-02 21:11:26]

Please, take a look.

[sky, 2011-06-02 22:16:08]

LGTM