Fix WebView::SetUserAgentAppName

Fix WebView::SetUserAgentAppName

WebView::SetUserAgentAppName was calling incorrect API, so fix it.

M34 commit ID: 146cf4767a84c1956c624f00e0b44bbe5282d38f
Issue: http://http://suprem.sec.samsung.net/jira/browse/CBWEBVIEW-893
Bug: http://107.108.218.239/bugzilla/show_bug.cgi?id=7744

Unit test: utc_blink_ewk_view_app_name_user_agent_set_func.cpp
Reviewed by:  Antonio Gomes, Viatcheslav Ostapenko, arno renevier, Yi Shen

Change-Id: I8ddd5bed16991fbcb723bf33492ce0b86cb181f5
Signed-off-by: zhuoyu.qian <zhuoyu.qian@samsung.com>