REGRESSION(274325@main): didFindString is always false when searching…

… in PDFs

rdar://122901465
https://bugs.webkit.org/show_bug.cgi?id=269310

Reviewed by Sammy Gill.

After 274325@main, API::FindClient::didFindString() is called in the completion handler of the final
FindString message if a match was found inside a frame. For PDFs, this frame ID was never set, so
didFindString would never be called. For now, if a match is found in a PDF, mark the main frame as the
frame containing the match.

* Source/WebKit/WebProcess/WebPage/FindController.cpp:
(WebKit::FindController::findString):

Canonical link: https://commits.webkit.org/274585@main

Source/WebKit/WebProcess/WebPage/FindController.cpp

@@ -285,9 +285,11 @@ void FindController::findString(const String& string, OptionSet<FindOptions> opt
     std::optional<FrameIdentifier> idOfFrameContainingString;
     DidWrap didWrap = DidWrap::No;
 #if ENABLE(PDF_PLUGIN)
-    if (pluginView)
+    if (pluginView) {
         found = pluginView->findString(string, coreOptions, maxMatchCount);
-    else
+        if (auto* frame = pluginView->frame(); frame && found)
+            idOfFrameContainingString = frame->frameID();
+    } else
 #endif
     {
         idOfFrameContainingString = m_webPage->corePage()->findString(string, coreOptions, &didWrap);