Remove URLRequestContextGetterEfl dependency on CookieManager

Remove URLRequestContextGetterEfl dependency on CookieManager

Right now, URLRequestContextGetterEfl depends on CookieManager
(scoped_refptr on it), and CookieManager depends on
URLRequestContextGetterEfl (with a WeakPtr).

This isn't a problem yet, because the headers are always called in a
specific way that. But trying to include
url_request_context_getter_efl.h in another file results in a build
error: invalid use of incomplete type ‘class CookieManager’ Trying
either to include url_request_context_getter_efl.h in cookie_manager.h
or cookie_manager.h in url_request_context_getter_efl.h doesn't work
because of the cycle dependency.

This patch removes URLRequestContextGetterEfl dependency on
CookieManager.

In order to avoid that kind of problem in the future, it also includes
headers needed for objects who have scoped_ptr members in
url_request_context_getter_efl.h

Change-Id: Ib2850258849981fee426238de6b91d86d15bafc8
Signed-off-by: Arnaud Renevier <a.renevier@samsung.com>