REGRESSION (263108@main): [ Ventura debug ] ASSERTION FAILED: WTF::We…

…akPtr<WebKit::RemoteScrollingCoordinatorProxy, WTF::DefaultWeakPtrImpl>::operator->() const

https://bugs.webkit.org/show_bug.cgi?id=255788
rdar://108369779

Reviewed by Tim Horton.

Add a missing bounce to the main thread before calling `scrollingTreeNodeDidBeginScrollSnapping` or
`scrollingTreeNodeDidEndScrollSnapping` in the UI process on macOS.

* Source/WebKit/UIProcess/RemoteLayerTree/mac/RemoteScrollingTreeMac.h:
* Source/WebKit/UIProcess/RemoteLayerTree/mac/RemoteScrollingTreeMac.mm:
(WebKit::RemoteScrollingTreeMac::scrollingTreeNodeWillStartScroll):
(WebKit::RemoteScrollingTreeMac::scrollingTreeNodeDidEndScroll):

Also harden some existing logic (as well as the new methods below) so that they explicitly protect
`this` when calling out to the main thread.

(WebKit::RemoteScrollingTreeMac::scrollingTreeNodeDidBeginScrollSnapping):
(WebKit::RemoteScrollingTreeMac::scrollingTreeNodeDidEndScrollSnapping):

Canonical link: https://commits.webkit.org/263271@main

Source/WebKit/UIProcess/RemoteLayerTree/mac/RemoteScrollingTreeMac.h

@@ -85,6 +85,9 @@ class RemoteScrollingTreeMac final : public RemoteScrollingTree {
     void scrollingTreeNodeWillStartScroll(WebCore::ScrollingNodeID) override;
     void scrollingTreeNodeDidEndScroll(WebCore::ScrollingNodeID) override;
 
+    void scrollingTreeNodeDidBeginScrollSnapping(ScrollingNodeID) override;
+    void scrollingTreeNodeDidEndScrollSnapping(ScrollingNodeID) override;
+
     Ref<WebCore::ScrollingTreeNode> createScrollingTreeNode(WebCore::ScrollingNodeType, WebCore::ScrollingNodeID) override;
 
     HashMap<WebCore::ScrollingNodeID, WebCore::RequestedScrollData> m_nodesWithPendingScrollAnimations; // Guarded by m_treeLock but used via call chains that can't be annotated.

Source/WebKit/UIProcess/RemoteLayerTree/mac/RemoteScrollingTreeMac.mm

@@ -73,18 +73,32 @@
 
 void RemoteScrollingTreeMac::scrollingTreeNodeWillStartScroll(ScrollingNodeID nodeID)
 {
-    RunLoop::main().dispatch([this, nodeID] {
+    RunLoop::main().dispatch([protectedThis = Ref { *this }, this, nodeID] {
         RemoteScrollingTree::scrollingTreeNodeWillStartScroll(nodeID);
     });
 }
 
 void RemoteScrollingTreeMac::scrollingTreeNodeDidEndScroll(ScrollingNodeID nodeID)
 {
-    RunLoop::main().dispatch([this, nodeID] {
+    RunLoop::main().dispatch([protectedThis = Ref { *this }, this, nodeID] {
         RemoteScrollingTree::scrollingTreeNodeDidEndScroll(nodeID);
     });
 }
 
+void RemoteScrollingTreeMac::scrollingTreeNodeDidBeginScrollSnapping(ScrollingNodeID nodeID)
+{
+    RunLoop::main().dispatch([protectedThis = Ref { *this }, this, nodeID] {
+        RemoteScrollingTree::scrollingTreeNodeDidBeginScrollSnapping(nodeID);
+    });
+}
+
+void RemoteScrollingTreeMac::scrollingTreeNodeDidEndScrollSnapping(ScrollingNodeID nodeID)
+{
+    RunLoop::main().dispatch([protectedThis = Ref { *this }, this, nodeID] {
+        RemoteScrollingTree::scrollingTreeNodeDidEndScrollSnapping(nodeID);
+    });
+}
+
 Ref<ScrollingTreeNode> RemoteScrollingTreeMac::createScrollingTreeNode(ScrollingNodeType nodeType, ScrollingNodeID nodeID)
 {
     switch (nodeType) {