GetWindowRect includes the window frames for maximized window even they are off screen, causing content outside the window being captured falsely. The fix is to remove the left/right/bottom window frame from the captured rect. Mouse capturing is adjusted accordingly as well.
BUG=3076
R=sergeyu@chromium.org
Review URL: https://webrtc-codereview.appspot.com/10149004
git-svn-id: http://webrtc.googlecode.com/svn/trunk@5732 4adac7df-926f-26a2-2b94-8c16560cd09d