third_party/WebKit/Source/core/dom/DocumentVisibilityObserver.h

   1 // Copyright 2015 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef DocumentVisibilityObserver_h
   6 #define DocumentVisibilityObserver_h
   7
   8 #include "core/CoreExport.h"
   9 #include "core/page/PageVisibilityState.h"
  10 #include "platform/heap/Handle.h"
  11
  12 namespace blink {
  13
  14 class Document;
  15
  16 class CORE_EXPORT DocumentVisibilityObserver : public WillBeGarbageCollectedMixin {
  17     WTF_MAKE_NONCOPYABLE(DocumentVisibilityObserver);
  18 public:
  19     explicit DocumentVisibilityObserver(Document&);
  20     virtual ~DocumentVisibilityObserver();
  21
  22     virtual void didChangeVisibilityState(PageVisibilityState) = 0;
  23
  24     // Classes that inherit Node and DocumentVisibilityObserver must have a
  25     // virtual override of Node::didMoveToNewDocument that calls
  26     // DocumentVisibilityObserver::setDocument
  27     void setObservedDocument(Document&);
  28
  29 protected:
  30     DECLARE_VIRTUAL_TRACE();
  31
  32 private:
  33     void registerObserver(Document&);
  34     void unregisterObserver();
  35
  36     RawPtrWillBeMember<Document> m_document;
  37 };
  38
  39 } // namespace blink
  40
  41 #endif // DocumentVisibilityObserver_h