Revert of Remove EventSender from ImageLoader

third_party/WebKit/Source/core/events/EventSender.h

+/*
+ * Copyright (C) 2012 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef EventSender_h
+#define EventSender_h
+
+#include "platform/Timer.h"
+#include "platform/heap/Handle.h"
+#include "platform/wtf/Vector.h"
+#include "platform/wtf/text/AtomicString.h"
+
+namespace blink {
+
+template <typename T>
+class EventSender final : public GarbageCollectedFinalized<EventSender<T>> {
+  WTF_MAKE_NONCOPYABLE(EventSender);
+
+ public:
+  static EventSender* Create(const AtomicString& event_type) {
+    return new EventSender(event_type);
+  }
+
+  const AtomicString& EventType() const { return event_type_; }
+  void DispatchEventSoon(T*);
+  void CancelEvent(T*);
+  void DispatchPendingEvents();
+
+#if DCHECK_IS_ON()
+  bool HasPendingEvents(T* sender) const {
+    return dispatch_soon_list_.Find(sender) != kNotFound ||
+           dispatching_list_.Find(sender) != kNotFound;
+  }
+#endif
+
+  DEFINE_INLINE_TRACE() {
+    visitor->Trace(dispatch_soon_list_);
+    visitor->Trace(dispatching_list_);
+  }
+
+ private:
+  explicit EventSender(const AtomicString& event_type);
+
+  void TimerFired(TimerBase*) { DispatchPendingEvents(); }
+
+  AtomicString event_type_;
+  Timer<EventSender<T>> timer_;
+  HeapVector<Member<T>> dispatch_soon_list_;
+  HeapVector<Member<T>> dispatching_list_;
+};
+
+template <typename T>
+EventSender<T>::EventSender(const AtomicString& event_type)
+    : event_type_(event_type), timer_(this, &EventSender::TimerFired) {}
+
+template <typename T>
+void EventSender<T>::DispatchEventSoon(T* sender) {
+  dispatch_soon_list_.push_back(sender);
+  if (!timer_.IsActive())
+    timer_.StartOneShot(0, BLINK_FROM_HERE);
+}
+
+template <typename T>
+void EventSender<T>::CancelEvent(T* sender) {
+  // Remove instances of this sender from both lists.
+  // Use loops because we allow multiple instances to get into the lists.
+  for (auto& sender_in_list : dispatch_soon_list_) {
+    if (sender_in_list == sender)
+      sender_in_list = nullptr;
+  }
+  for (auto& sender_in_list : dispatching_list_) {
+    if (sender_in_list == sender)
+      sender_in_list = nullptr;
+  }
+}
+
+template <typename T>
+void EventSender<T>::DispatchPendingEvents() {
+  // Need to avoid re-entering this function; if new dispatches are
+  // scheduled before the parent finishes processing the list, they
+  // will set a timer and eventually be processed.
+  if (!dispatching_list_.IsEmpty())
+    return;
+
+  timer_.Stop();
+
+  dispatching_list_.swap(dispatch_soon_list_);
+  for (auto& sender_in_list : dispatching_list_) {
+    if (T* sender = sender_in_list) {
+      sender_in_list = nullptr;
+      sender->DispatchPendingEvent(this);
+    }
+  }
+  dispatching_list_.clear();
+}
+
+}  // namespace blink
+
+#endif  // EventSender_h