WinAura: Fix task manager frame color

It was using a Chrome OS gray instead of a Windows blue.

BUG=323318
TEST=manual

Review URL: https://codereview.chromium.org/88553004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237467 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237467