[M73 Dev][EFL] Attach MessagePump::Delegate to MessagePumpForUIEfl

[M73 Dev][EFL] Attach MessagePump::Delegate to MessagePumpForUIEfl

Due to changes in chromium upstream, MessageLoop is no longer
a MessagePump::Delegate. Therefore, below piece of code becomes
invalid and had to be removed.

Delegate* delegate = MessageLoopForUI::current();

Due to this, calls to Delegate methods are not made which breaks
the loop and ecore_pipe_write() does not get executed resulting
in white screen at webview launch.

This commit attaches MessagePump::Delegate to MessagePumpForUIEfl.

Change-Id: I674dac8ca736a5c6ff2172c5f5938325b706b5ab
Signed-off-by: Chandan Padhi <c.padhi@samsung.com>