Use a reference instead of a pointer in core/dom/events.

They never be nullptr. There are still other places which should be
a reference, which can be done in another CL.

Bug: 874385
Change-Id: I278e022b40a621115d627ac21cdbb9658f98733e
Reviewed-on: https://chromium-review.googlesource.com/c/1333167
Commit-Queue: Hayato Ito <hayato@chromium.org>
Reviewed-by: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607478}

third_party/blink/renderer/core/animation/css/css_animations.cc

@@ -1119,7 +1119,7 @@ void CSSAnimations::CalculateTransitionActiveInterpolations(
 }
 
 EventTarget* CSSAnimations::AnimationEventDelegate::GetEventTarget() const {
-  return EventPath::EventTargetRespectingTargetRules(*animation_target_);
+  return &EventPath::EventTargetRespectingTargetRules(*animation_target_);
 }
 
 void CSSAnimations::AnimationEventDelegate::MaybeDispatch(
@@ -1189,7 +1189,7 @@ void CSSAnimations::AnimationEventDelegate::Trace(blink::Visitor* visitor) {
 }
 
 EventTarget* CSSAnimations::TransitionEventDelegate::GetEventTarget() const {
-  return EventPath::EventTargetRespectingTargetRules(*transition_target_);
+  return &EventPath::EventTargetRespectingTargetRules(*transition_target_);
 }
 
 void CSSAnimations::TransitionEventDelegate::OnEventCondition(

third_party/blink/renderer/core/dom/events/event_dispatcher.cc

@@ -70,7 +70,7 @@ EventDispatcher::EventDispatcher(Node& node, Event& event)
 void EventDispatcher::DispatchScopedEvent(Node& node, Event& event) {
   // We need to set the target here because it can go away by the time we
   // actually fire the event.
-  event.SetTarget(EventPath::EventTargetRespectingTargetRules(node));
+  event.SetTarget(&EventPath::EventTargetRespectingTargetRules(node));
   ScopedEventQueue::Instance()->EnqueueEvent(event);
 }
 
@@ -192,7 +192,7 @@ DispatchEventResult EventDispatcher::Dispatch() {
     }
   }
 
-  event_->SetTarget(EventPath::EventTargetRespectingTargetRules(*node_));
+  event_->SetTarget(&EventPath::EventTargetRespectingTargetRules(*node_));
 #if DCHECK_IS_ON()
   DCHECK(!EventDispatchForbiddenScope::IsEventDispatchForbidden());
 #endif
@@ -306,7 +306,7 @@ inline void EventDispatcher::DispatchEventAtBubbling() {
 inline void EventDispatcher::DispatchEventPostProcess(
     Node* activation_target,
     EventDispatchHandlingState* pre_dispatch_event_handler_result) {
-  event_->SetTarget(EventPath::EventTargetRespectingTargetRules(*node_));
+  event_->SetTarget(&EventPath::EventTargetRespectingTargetRules(*node_));
   // https://dom.spec.whatwg.org/#concept-event-dispatch
   // 14. Unset event’s dispatch flag, stop propagation flag, and stop immediate
   // propagation flag.

third_party/blink/renderer/core/dom/events/event_path.cc

@@ -38,13 +38,13 @@
 
 namespace blink {
 
-EventTarget* EventPath::EventTargetRespectingTargetRules(Node& reference_node) {
+EventTarget& EventPath::EventTargetRespectingTargetRules(Node& reference_node) {
   if (reference_node.IsPseudoElement()) {
     DCHECK(reference_node.parentNode());
-    return reference_node.parentNode();
+    return *reference_node.parentNode();
   }
 
-  return &reference_node;
+  return reference_node;
 }
 
 static inline bool ShouldStopAtShadowRoot(Event& event,
@@ -133,8 +133,9 @@ void EventPath::CalculatePath() {
 
   node_event_contexts_.ReserveCapacity(nodes_in_path.size());
   for (Node* node_in_path : nodes_in_path) {
+    DCHECK(node_in_path);
     node_event_contexts_.push_back(NodeEventContext(
-        node_in_path, EventTargetRespectingTargetRules(*node_in_path)));
+        *node_in_path, EventTargetRespectingTargetRules(*node_in_path)));
   }
 }
 
@@ -189,7 +190,7 @@ TreeScopeEventContext* EventPath::EnsureTreeScopeEventContext(
     if (parent_tree_scope_event_context &&
         parent_tree_scope_event_context->Target()) {
       tree_scope_event_context->SetTarget(
-          parent_tree_scope_event_context->Target());
+          *parent_tree_scope_event_context->Target());
     } else if (current_target) {
       tree_scope_event_context->SetTarget(
           EventTargetRespectingTargetRules(*current_target));
@@ -273,7 +274,7 @@ void EventPath::RetargetRelatedTarget(const Node& related_target_node) {
     EventTarget* adjusted_related_target = FindRelatedNode(
         tree_scope_event_context->GetTreeScope(), related_node_map);
     DCHECK(adjusted_related_target);
-    tree_scope_event_context.Get()->SetRelatedTarget(adjusted_related_target);
+    tree_scope_event_context.Get()->SetRelatedTarget(*adjusted_related_target);
   }
 }
 

third_party/blink/renderer/core/dom/events/event_path.h

@@ -82,7 +82,7 @@ class CORE_EXPORT EventPath final
 
   NodeEventContext& TopNodeEventContext();
 
-  static EventTarget* EventTargetRespectingTargetRules(Node&);
+  static EventTarget& EventTargetRespectingTargetRules(Node&);
 
   void Trace(blink::Visitor*);
   void Clear() {

third_party/blink/renderer/core/dom/events/node_event_context.cc

@@ -35,10 +35,8 @@
 
 namespace blink {
 
-NodeEventContext::NodeEventContext(Node* node, EventTarget* current_target)
-    : node_(node), current_target_(current_target) {
-  DCHECK(node_);
-}
+NodeEventContext::NodeEventContext(Node& node, EventTarget& current_target)
+    : node_(node), current_target_(current_target) {}
 
 void NodeEventContext::Trace(blink::Visitor* visitor) {
   visitor->Trace(node_);

third_party/blink/renderer/core/dom/events/node_event_context.h

@@ -42,7 +42,7 @@ class CORE_EXPORT NodeEventContext {
 
  public:
   // FIXME: Use ContainerNode instead of Node.
-  NodeEventContext(Node*, EventTarget* current_target);
+  NodeEventContext(Node&, EventTarget& current_target);
   void Trace(blink::Visitor*);
 
   Node* GetNode() const { return node_.Get(); }

third_party/blink/renderer/core/dom/events/tree_scope_event_context.h

@@ -54,10 +54,10 @@ class CORE_EXPORT TreeScopeEventContext final
   ContainerNode& RootNode() const { return tree_scope_->RootNode(); }
 
   EventTarget* Target() const { return target_.Get(); }
-  void SetTarget(EventTarget*);
+  void SetTarget(EventTarget&);
 
   EventTarget* RelatedTarget() const { return related_target_.Get(); }
-  void SetRelatedTarget(EventTarget*);
+  void SetRelatedTarget(EventTarget&);
 
   TouchEventContext* GetTouchEventContext() const {
     return touch_event_context_.Get();
@@ -118,16 +118,14 @@ inline void TreeScopeEventContext::CheckReachableNode(EventTarget& target) {
 inline void TreeScopeEventContext::CheckReachableNode(EventTarget&) {}
 #endif
 
-inline void TreeScopeEventContext::SetTarget(EventTarget* target) {
-  DCHECK(target);
-  CheckReachableNode(*target);
+inline void TreeScopeEventContext::SetTarget(EventTarget& target) {
+  CheckReachableNode(target);
   target_ = target;
 }
 
 inline void TreeScopeEventContext::SetRelatedTarget(
-    EventTarget* related_target) {
-  DCHECK(related_target);
-  CheckReachableNode(*related_target);
+    EventTarget& related_target) {
+  CheckReachableNode(related_target);
   related_target_ = related_target;
 }