Bump process priority during WebPageProxy::getContentsAsAttributedStr…

…ing()

https://bugs.webkit.org/show_bug.cgi?id=259294
rdar://110464974

Reviewed by Brent Fulgham.

Bump process priority during WebPageProxy::getContentsAsAttributedString() so
that the app doesn't hang waiting for a reply if the view is background.

* Source/WebKit/UIProcess/WebPageProxy.cpp:
(WebKit::WebPageProxy::getContentsAsAttributedString):

Canonical link: https://commits.webkit.org/266115@main

Source/WebKit/UIProcess/WebPageProxy.cpp

@@ -5073,7 +5073,9 @@ void WebPageProxy::getContentsAsAttributedString(CompletionHandler<void(const We
         return;
     }
 
-    sendWithAsyncReply(Messages::WebPage::GetContentsAsAttributedString(), WTFMove(completionHandler));
+    sendWithAsyncReply(Messages::WebPage::GetContentsAsAttributedString(), [completionHandler = WTFMove(completionHandler), activity = process().throttler().foregroundActivity("getContentsAsAttributedString"_s)](const WebCore::AttributedString& string) mutable {
+        completionHandler(string);
+    });
 }
 #endif