[Downloads] "Open with system handler" isn't necessary on Chrome OS.

Chrome prefers opening downloaded PDFs in the browser. An "Open with
system handler" option is available when using the system handler is
desired. Disable this option on Chrome OS since the behavior of this
option is the same as opening in the browser.

BUG=none

Review URL: https://codereview.chromium.org/75483008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236801 0039d316-1c4b-4281-b951-d872f2087c98
Use the regular window header for maximized v1 apps

BUG=321799
TEST=Manual, see bug

Review URL: https://codereview.chromium.org/77733011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@236802 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 236802