[login_manager] Stop passing --main-menu-url to chrome
[login_manager] Stop passing --main-menu-url to chrome

BUG=None
TEST=start chrome os, make sure the browser runs

Change-Id: I7aa140f878b2178dd39210d13398828d765d7f66

Review URL: http://codereview.chromium.org/3157031

chadversary/chromiumos.platform.login_manager,joshfire/chromiumos-platform-login_manager,chadversary/chromiumos.platform.login_manager,joshfire/chromiumos-platform-login_manager,joshfire/chromiumos-platform-login_manager,chadversary/chromiumos.platform.login_manager