Move off of UIKit SPI: UIURLDragPreviewView

https://bugs.webkit.org/show_bug.cgi?id=260448
rdar://114165890

Reviewed by Aditya Keerthi and Tim Horton.

Replace usages of `UIURLDragPreviewView` in WebKit with `+[UIDragPreview previewForURL:title:]`.

* Source/WebKit/Platform/spi/ios/UIKitSPI.h:

Remove the (now-unused) SPI declaration and header include.

* Source/WebKit/UIProcess/ios/DragDropInteractionState.h:
* Source/WebKit/UIProcess/ios/DragDropInteractionState.mm:
(WebKit::DragDropInteractionState::stageDragItem):

We no longer need to plumb the `center` point into the preview provider block, so we can also remove
the `adjustedOrigin` member while we're here.

(WebKit::DragDropInteractionState::updatePreviewsForActiveDragSources):

Use `+[UIDragPreview previewForURL:title:]` instead of directly creating a `UIURLDragPreviewView`.
There is a caveat here, which is that on visionOS (where we need to override the background color of
the preview by setting `-backgroundColor` on the preview parameters), we need to first use
`+previewForURL:title:` to make UIKit instantiate a `UIURLDragPreviewView`, which we can then use to
initialize a `UIDragPreview`.

Canonical link: https://commits.webkit.org/267102@main

Source/WebKit/Platform/spi/ios/UIKitSPI.h

@@ -125,8 +125,6 @@
 #import <UIKit/UIDragPreview_Private.h>
 #import <UIKit/UIDragSession.h>
 #import <UIKit/UIDropInteraction.h>
-#import <UIKit/UIPreviewInteraction.h>
-#import <UIKit/UIURLDragPreviewView.h>
 #import <UIKit/_UITextDragCaretView.h>
 #endif
 
@@ -1103,10 +1101,6 @@ WTF_EXTERN_C_END
 -(void)remove;
 @end
 
-@interface UIURLDragPreviewView : UIView
-+ (instancetype)viewWithTitle:(NSString *)title URL:(NSURL *)url;
-@end
-
 @interface _UIParallaxTransitionPanGestureRecognizer : UIScreenEdgePanGestureRecognizer
 @end
 

Source/WebKit/UIProcess/ios/DragDropInteractionState.h

@@ -47,7 +47,6 @@ namespace WebKit {
 
 struct DragSourceState {
     OptionSet<WebCore::DragSourceAction> action;
-    CGPoint adjustedOrigin { CGPointZero };
     CGRect dragPreviewFrameInRootViewCoordinates { CGRectZero };
     RetainPtr<UIImage> image;
     std::optional<WebCore::TextIndicatorData> indicatorData;

Source/WebKit/UIProcess/ios/DragDropInteractionState.mm

@@ -351,7 +351,6 @@ static bool canUpdatePreviewForActiveDragSource(const DragSourceState& source)
     m_adjustedPositionForDragEnd = item.eventPositionInContentCoordinates;
     m_stagedDragSource = {{
         item.sourceAction,
-        item.eventPositionInContentCoordinates,
         item.dragPreviewFrameInRootViewCoordinates,
         dragImage,
         item.image.indicatorData(),
@@ -403,15 +402,20 @@ static bool canUpdatePreviewForActiveDragSource(const DragSourceState& source)
             continue;
 
         if (source.action.contains(DragSourceAction::Link)) {
-            dragItem.previewProvider = [title = retainPtr((NSString *)source.linkTitle), url = retainPtr((NSURL *)source.linkURL), center = source.adjustedOrigin] () -> UIDragPreview * {
-                UIURLDragPreviewView *previewView = [UIURLDragPreviewView viewWithTitle:title.get() URL:url.get()];
-                previewView.center = center;
-                auto parameters = adoptNS([[UIDragPreviewParameters alloc] initWithTextLineRects:@[ [NSValue valueWithCGRect:previewView.bounds] ]]);
-                [parameters setBackgroundColor:[UIColor colorWithDynamicProvider:[] (UITraitCollection *traitCollection) -> UIColor * {
+            dragItem.previewProvider = [title = retainPtr((NSString *)source.linkTitle), url = retainPtr((NSURL *)source.linkURL)] () -> UIDragPreview * {
+                RetainPtr preview = [UIDragPreview previewForURL:url.get() title:title.get()];
+#if PLATFORM(VISION)
+                // FIXME: This is a slightly unfortunate since we end up copying the preview parameters,
+                // and also create an extra `UIDragPreview` on visionOS. We can remove this workaround
+                // once UIKit addresses <rdar://114204432>.
+                auto adjustedParameters = [preview parameters];
+                adjustedParameters.backgroundColor = [UIColor colorWithDynamicProvider:[] (UITraitCollection *traitCollection) -> UIColor * {
                     WebCore::LocalCurrentTraitCollection localCurrentTraitCollection(traitCollection);
                     return [UIColor.systemBackgroundColor resolvedColorWithTraitCollection:UITraitCollection.currentTraitCollection];
                 }]];
-                return adoptNS([[UIDragPreview alloc] initWithView:previewView parameters:parameters.get()]).autorelease();
+                preview = adoptNS([[UIDragPreview alloc] initWithView:[preview view] parameters:adjustedParameters]);
+#endif // PLATFORM(VISION)
+                return preview.autorelease();
             };
         }
 #if ENABLE(INPUT_TYPE_COLOR)