Fixing opacity for browser frame window on ASH/Windows.

Reviewers=scottmg, sky, cpu
TBR=pfeldman
BUG=324103

Review URL: https://codereview.chromium.org/108193005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@241535 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 241535