[Safer CPP] Address ForwardDeclChecker warnings under UnifiedPDF files

https://bugs.webkit.org/show_bug.cgi?id=290288
rdar://147691279

Reviewed by Chris Dumez.

Note that this is a best effort attempt, and we will still have warnings
in UnifiedPDFPlugin.mm and in PDFDataDetectorOverlayController.mm. The
warnings that persist are false positives surfaced in open source
configurations, though, since types such as CGPDFPageLayoutRef and
DDHighlightRef are defined in private framework headers.

* Source/WebKit/SaferCPPExpectations/ForwardDeclCheckerExpectations:
* Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/PDFPresentationController.mm:
* Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/UnifiedPDFPlugin.mm:

Canonical link: https://commits.webkit.org/292571@main

Author: aprotyas

Source/WebKit/SaferCPPExpectations/ForwardDeclCheckerExpectations

@@ -30,7 +30,6 @@ UIProcess/WebProcessPool.h
 WebProcess/Extensions/Bindings/JSWebExtensionWrapper.h
 WebProcess/Inspector/WebInspectorClient.cpp
 WebProcess/Plugins/PDF/UnifiedPDF/PDFDataDetectorOverlayController.mm
-WebProcess/Plugins/PDF/UnifiedPDF/PDFPresentationController.mm
 WebProcess/Plugins/PDF/UnifiedPDF/UnifiedPDFPlugin.mm
 WebProcess/WebAuthentication/WebAuthenticatorCoordinator.cpp
 WebProcess/WebCoreSupport/WebChromeClient.cpp

Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/PDFPresentationController.mm

@@ -33,6 +33,7 @@
 #include "PDFKitSPI.h"
 #include "PDFScrollingPresentationController.h"
 #include <WebCore/GraphicsLayer.h>
+#include <WebCore/GraphicsLayerFactory.h>
 #include <WebCore/LocalFrameView.h>
 #include <wtf/CheckedRef.h>
 #include <wtf/TZoneMallocInlines.h>

Source/WebKit/WebProcess/Plugins/PDF/UnifiedPDF/UnifiedPDFPlugin.mm

@@ -80,6 +80,7 @@
 #include <WebCore/GraphicsContext.h>
 #include <WebCore/GraphicsLayer.h>
 #include <WebCore/GraphicsLayerClient.h>
+#include <WebCore/GraphicsLayerFactory.h>
 #include <WebCore/GraphicsTypes.h>
 #include <WebCore/HTMLNames.h>
 #include <WebCore/HTMLPlugInElement.h>