Allow resizing of packaged app windows in Windows desktop mode

Install an EasyResizeWindowTargeter on the containing
root window to allow for selection handles to appear
at the edges of the client area, allowing packaged
apps to be resized.

BUG=338671
TEST=ShapedAppWindowTargeterTest.ResizeInsetsWithinBounds

Review URL: https://codereview.chromium.org/167633002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252458 0039d316-1c4b-4281-b951-d872f2087c98
Set |bufsize| to 0 when we set |buf| to NULL.

R=agl@chromium.org
BUG=none
TEST=none

Review URL: https://codereview.chromium.org/173713006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@252459 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 252458
SVN changes up to revision 252459