PDFs should be downloaded in lockdown mode

https://bugs.webkit.org/show_bug.cgi?id=271003
rdar://124636755

Reviewed by Chris Dumez.

This functionality was first introduced in https://bugs.webkit.org/show_bug.cgi?id=237245, but
was disabled for macOS in https://bugs.webkit.org/show_bug.cgi?id=241741. This patch is to re-enable it.

This functionality should be covered by WKDownload.LockdownModePDF. Which is also fixed in this change
such that it fails whenever the conditional doesn't exist.

* Source/WebKit/UIProcess/WebPageProxy.cpp:
(WebKit::WebPageProxy::decidePolicyForResponseShared):
* Tools/TestWebKitAPI/Tests/WebKitCocoa/Download.mm:

Canonical link: https://commits.webkit.org/272448.740@safari-7618-branch

Source/WebKit/UIProcess/WebPageProxy.cpp

@@ -7038,11 +7038,23 @@ void WebPageProxy::decidePolicyForResponseShared(Ref<WebProcessProxy>&& process,
         RELEASE_ASSERT(processSwapRequestedByClient == ProcessSwapRequestedByClient::No);
         ASSERT_UNUSED(safeBrowsingWarning, !safeBrowsingWarning);
 
-        Ref sender = PolicyDecisionSender::create(WTFMove(completionHandler));
+        bool shouldForceDownload = [&] {
+            if (policyAction != PolicyAction::Use || process->lockdownMode() != WebProcessProxy::LockdownMode::Enabled)
+                return false;
+            if (MIMETypeRegistry::isPDFOrPostScriptMIMEType(navigationResponse->response().mimeType()))
+                return true;
+            if (MIMETypeRegistry::isSupportedModelMIMEType(navigationResponse->response().mimeType()))
+                return true;
 #if USE(QUICK_LOOK)
-        if (policyAction == PolicyAction::Use && process->lockdownMode() == WebProcessProxy::LockdownMode::Enabled && (MIMETypeRegistry::isPDFOrPostScriptMIMEType(navigationResponse->response().mimeType()) || MIMETypeRegistry::isSupportedModelMIMEType(navigationResponse->response().mimeType()) || PreviewConverter::supportsMIMEType(navigationResponse->response().mimeType())))
-            policyAction = PolicyAction::Download;
+            if (PreviewConverter::supportsMIMEType(navigationResponse->response().mimeType()))
+                return true;
 #endif
+            return false;
+        }();
+        if (shouldForceDownload)
+            policyAction = PolicyAction::Download;
+
+        Ref sender = PolicyDecisionSender::create(WTFMove(completionHandler));
         receivedPolicyDecision(policyAction, navigation.get(), nullptr, WTFMove(navigationResponse), WTFMove(sender), WillContinueLoadInNewProcess::No, std::nullopt);
     }, ShouldExpectSafeBrowsingResult::No, ShouldExpectAppBoundDomainResult::No, ShouldWaitForInitialLinkDecorationFilteringData::No);
 

Tools/TestWebKitAPI/Tests/WebKitCocoa/Download.mm

@@ -2745,6 +2745,10 @@ HTTPServer childFrameServer({
     auto server = simplePDFTestServer();
     NSURL *expectedDownloadFile = tempPDFThatDoesNotExist();
 
+    delegate.get().decidePolicyForNavigationResponse = ^(WKNavigationResponse *, void (^completionHandler)(WKNavigationResponsePolicy)) {
+        completionHandler(WKNavigationResponsePolicyAllow);
+    };
+
     delegate.get().navigationResponseDidBecomeDownload = ^(WKWebView *, WKNavigationResponse *, WKDownload *download) {
         download.delegate = delegate.get();
         delegate.get().decideDestinationUsingResponse = ^(WKDownload *download, NSURLResponse *, NSString *, void (^completionHandler)(NSURL *)) {