Update window region after widget resizes not changing HWND size
When width or height of a widget is changed to a value less than 64
pixels, it is rounded up to 64 pixels (see crbug.com/286609). This might
cause the actual HWND size remain the same while changing size of the
widget. In this case, we need to force message handler to update window
region since we are not receiving resize messages form the OS.
BUG=376329
Review URL: https://codereview.chromium.org/
300163002
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@273081 0039d316-1c4b-4281-b951-d872f2087c98