Removed obsolete flag for Chrome.
Removed obsolete flag for Chrome.

Change-Id: I819dba9ecd03e4587c04dc3ebfdaf18afc2b0c70

BUG=chromium-os:7214
TEST=Check that --enable-login-images flag is not passed to Chrome.

Review URL: http://codereview.chromium.org/6261005

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