Make more use of smart pointers in Source/WebKit/UIProcess/WebProcessProxy.cpp
Pull request: https://github.com/WebKit/WebKit/pull/16875
Committed 267141@main (13039308c5f5): <https://commits.webkit.org/267141@main> Reviewed commits have been landed. Closing PR #16875 and removing active labels.
<rdar://problem/114270912>