Source/WebCore/history/HistoryItem.h - WebKit - Git at Google

 /*
  * Copyright (C) 2006, 2008, 2011, 2014 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Research In Motion Limited. 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. ``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
  * 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.
  */

 #pragma once

 #include "BackForwardItemIdentifier.h"
 #include "FloatRect.h"
 #include "FrameLoaderTypes.h"
 #include "IntPoint.h"
 #include "IntRect.h"
 #include "LengthBox.h"
 #include "SerializedScriptValue.h"
 #include <memory>
 #include <wtf/RefCounted.h>
 #include <wtf/text/WTFString.h>

 #if PLATFORM(IOS_FAMILY)
 #include "ViewportArguments.h"
 #endif

 #if PLATFORM(COCOA)
 #import <wtf/RetainPtr.h>
 typedef struct objc_object* id;
 #endif

 namespace WebCore {

 class CachedPage;
 class Document;
 class FormData;
 class HistoryItem;
 class Image;
 class ResourceRequest;
 enum class PruningReason;

 WEBCORE_EXPORT extern void (*notifyHistoryItemChanged)(HistoryItem&);

 class HistoryItem : public RefCounted<HistoryItem> {
     friend class PageCache;

 public:
     static Ref<HistoryItem> create()
     {
         return adoptRef(*new HistoryItem);
     }

     static Ref<HistoryItem> create(const String& urlString, const String& title)
     {
         return adoptRef(*new HistoryItem(urlString, title));
     }

     static Ref<HistoryItem> create(const String& urlString, const String& title, const String& alternateTitle)
     {
         return adoptRef(*new HistoryItem(urlString, title, alternateTitle));
     }

     static Ref<HistoryItem> create(const String& urlString, const String& title, const String& alternateTitle, BackForwardItemIdentifier identifier)
     {
         return adoptRef(*new HistoryItem(urlString, title, alternateTitle, identifier));
     }

     WEBCORE_EXPORT ~HistoryItem();

     WEBCORE_EXPORT Ref<HistoryItem> copy() const;

     const BackForwardItemIdentifier& identifier() const { return m_identifier; }

     // Resets the HistoryItem to its initial state, as returned by create().
     void reset();

     WEBCORE_EXPORT const String& originalURLString() const;
     WEBCORE_EXPORT const String& urlString() const;
     WEBCORE_EXPORT const String& title() const;

     bool isInPageCache() const { return m_cachedPage.get(); }
     WEBCORE_EXPORT bool hasCachedPageExpired() const;

     WEBCORE_EXPORT void setAlternateTitle(const String&);
     WEBCORE_EXPORT const String& alternateTitle() const;

     WEBCORE_EXPORT URL url() const;
     WEBCORE_EXPORT URL originalURL() const;
     WEBCORE_EXPORT const String& referrer() const;
     WEBCORE_EXPORT const String& target() const;
     WEBCORE_EXPORT bool isTargetItem() const;

     WEBCORE_EXPORT FormData* formData();
     WEBCORE_EXPORT String formContentType() const;

     bool lastVisitWasFailure() const { return m_lastVisitWasFailure; }

     WEBCORE_EXPORT const IntPoint& scrollPosition() const;
     WEBCORE_EXPORT void setScrollPosition(const IntPoint&);
     void clearScrollPosition();

     WEBCORE_EXPORT bool shouldRestoreScrollPosition() const;
     WEBCORE_EXPORT void setShouldRestoreScrollPosition(bool);

     WEBCORE_EXPORT float pageScaleFactor() const;
     WEBCORE_EXPORT void setPageScaleFactor(float);

     WEBCORE_EXPORT const Vector<String>& documentState() const;
     WEBCORE_EXPORT void setDocumentState(const Vector<String>&);
     void clearDocumentState();

     WEBCORE_EXPORT void setShouldOpenExternalURLsPolicy(ShouldOpenExternalURLsPolicy);
     WEBCORE_EXPORT ShouldOpenExternalURLsPolicy shouldOpenExternalURLsPolicy() const;

     void setURL(const URL&);
     WEBCORE_EXPORT void setURLString(const String&);
     WEBCORE_EXPORT void setOriginalURLString(const String&);
     WEBCORE_EXPORT void setReferrer(const String&);
     WEBCORE_EXPORT void setTarget(const String&);
     WEBCORE_EXPORT void setTitle(const String&);
     WEBCORE_EXPORT void setIsTargetItem(bool);

     WEBCORE_EXPORT void setStateObject(RefPtr<SerializedScriptValue>&&);
     SerializedScriptValue* stateObject() const { return m_stateObject.get(); }

     void setItemSequenceNumber(long long number) { m_itemSequenceNumber = number; }
     long long itemSequenceNumber() const { return m_itemSequenceNumber; }

     void setDocumentSequenceNumber(long long number) { m_documentSequenceNumber = number; }
     long long documentSequenceNumber() const { return m_documentSequenceNumber; }

     void setFormInfoFromRequest(const ResourceRequest&);
     WEBCORE_EXPORT void setFormData(RefPtr<FormData>&&);
     WEBCORE_EXPORT void setFormContentType(const String&);

     void setLastVisitWasFailure(bool wasFailure) { m_lastVisitWasFailure = wasFailure; }

     WEBCORE_EXPORT void addChildItem(Ref<HistoryItem>&&);
     void setChildItem(Ref<HistoryItem>&&);
     WEBCORE_EXPORT HistoryItem* childItemWithTarget(const String&);
     HistoryItem* childItemWithDocumentSequenceNumber(long long number);
     WEBCORE_EXPORT const Vector<Ref<HistoryItem>>& children() const;
     WEBCORE_EXPORT bool hasChildren() const;
     void clearChildren();

     bool shouldDoSameDocumentNavigationTo(HistoryItem& otherItem) const;
     bool hasSameFrames(HistoryItem& otherItem) const;

     bool isCurrentDocument(Document&) const;

 #if PLATFORM(COCOA)
     WEBCORE_EXPORT id viewState() const;
     WEBCORE_EXPORT void setViewState(id);
 #endif

 #ifndef NDEBUG
     int showTree() const;
     int showTreeWithIndent(unsigned indentLevel) const;
 #endif

 #if PLATFORM(IOS_FAMILY)
     FloatRect exposedContentRect() const { return m_exposedContentRect; }
     void setExposedContentRect(FloatRect exposedContentRect) { m_exposedContentRect = exposedContentRect; }

     IntRect unobscuredContentRect() const { return m_unobscuredContentRect; }
     void setUnobscuredContentRect(IntRect unobscuredContentRect) { m_unobscuredContentRect = unobscuredContentRect; }

     const FloatBoxExtent& obscuredInsets() const { return m_obscuredInsets; }
     void setObscuredInsets(const FloatBoxExtent& insets) { m_obscuredInsets = insets; }

     FloatSize minimumLayoutSizeInScrollViewCoordinates() const { return m_minimumLayoutSizeInScrollViewCoordinates; }
     void setMinimumLayoutSizeInScrollViewCoordinates(FloatSize minimumLayoutSizeInScrollViewCoordinates) { m_minimumLayoutSizeInScrollViewCoordinates = minimumLayoutSizeInScrollViewCoordinates; }

     IntSize contentSize() const { return m_contentSize; }
     void setContentSize(IntSize contentSize) { m_contentSize = contentSize; }

     float scale() const { return m_scale; }
     bool scaleIsInitial() const { return m_scaleIsInitial; }
     void setScaleIsInitial(bool scaleIsInitial) { m_scaleIsInitial = scaleIsInitial; }
     void setScale(float newScale, bool isInitial)
     {
         m_scale = newScale;
         m_scaleIsInitial = isInitial;
     }

     const ViewportArguments& viewportArguments() const { return m_viewportArguments; }
     void setViewportArguments(const ViewportArguments& viewportArguments) { m_viewportArguments = viewportArguments; }
 #endif

     void notifyChanged();

     void setWasRestoredFromSession(bool wasRestoredFromSession) { m_wasRestoredFromSession = wasRestoredFromSession; }
     bool wasRestoredFromSession() const { return m_wasRestoredFromSession; }

 #if !LOG_DISABLED
     const char* logString() const;
 #endif

 private:
     WEBCORE_EXPORT HistoryItem();
     WEBCORE_EXPORT HistoryItem(const String& urlString, const String& title);
     WEBCORE_EXPORT HistoryItem(const String& urlString, const String& title, const String& alternateTitle);
     WEBCORE_EXPORT HistoryItem(const String& urlString, const String& title, const String& alternateTitle, BackForwardItemIdentifier);

     void setCachedPage(std::unique_ptr<CachedPage>&&);
     std::unique_ptr<CachedPage> takeCachedPage();

     HistoryItem(const HistoryItem&);

     static int64_t generateSequenceNumber();

     bool hasSameDocumentTree(HistoryItem& otherItem) const;

     String m_urlString;
     String m_originalURLString;
     String m_referrer;
     String m_target;
     String m_title;
     String m_displayTitle;

     IntPoint m_scrollPosition;
     float m_pageScaleFactor { 0 }; // 0 indicates "unset".
     Vector<String> m_documentState;

     ShouldOpenExternalURLsPolicy m_shouldOpenExternalURLsPolicy { ShouldOpenExternalURLsPolicy::ShouldNotAllow };

     Vector<Ref<HistoryItem>> m_children;

     bool m_lastVisitWasFailure { false };
     bool m_isTargetItem { false };
     bool m_wasRestoredFromSession { false };
     bool m_shouldRestoreScrollPosition { true };

     // If two HistoryItems have the same item sequence number, then they are
     // clones of one another.  Traversing history from one such HistoryItem to
     // another is a no-op.  HistoryItem clones are created for parent and
     // sibling frames when only a subframe navigates.
     int64_t m_itemSequenceNumber { generateSequenceNumber() };

     // If two HistoryItems have the same document sequence number, then they
     // refer to the same instance of a document.  Traversing history from one
     // such HistoryItem to another preserves the document.
     int64_t m_documentSequenceNumber { generateSequenceNumber() };

     // Support for HTML5 History
     RefPtr<SerializedScriptValue> m_stateObject;

     // info used to repost form data
     RefPtr<FormData> m_formData;
     String m_formContentType;

     // PageCache controls these fields.
     std::unique_ptr<CachedPage> m_cachedPage;
     PruningReason m_pruningReason;

 #if PLATFORM(IOS_FAMILY)
     FloatRect m_exposedContentRect;
     IntRect m_unobscuredContentRect;
     FloatSize m_minimumLayoutSizeInScrollViewCoordinates;
     IntSize m_contentSize;
     FloatBoxExtent m_obscuredInsets;
     float m_scale { 0 }; // Note that UIWebView looks for a non-zero value, so this has to start as 0.
     bool m_scaleIsInitial { false };
     ViewportArguments m_viewportArguments;
 #endif

 #if PLATFORM(COCOA)
     RetainPtr<id> m_viewState;
 #endif

     BackForwardItemIdentifier m_identifier;
 };

 } // namespace WebCore

 #if ENABLE(TREE_DEBUGGING)
 // Outside the WebCore namespace for ease of invocation from the debugger.
 extern "C" int showTree(const WebCore::HistoryItem*);
 #endif
	/*
	* Copyright (C) 2006, 2008, 2011, 2014 Apple Inc. All rights reserved.
	* Copyright (C) 2012 Research In Motion Limited. 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. ``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
	* 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.
	*/

	#pragma once

	#include "BackForwardItemIdentifier.h"
	#include "FloatRect.h"
	#include "FrameLoaderTypes.h"
	#include "IntPoint.h"
	#include "IntRect.h"
	#include "LengthBox.h"
	#include "SerializedScriptValue.h"
	#include <memory>
	#include <wtf/RefCounted.h>
	#include <wtf/text/WTFString.h>

	#if PLATFORM(IOS_FAMILY)
	#include "ViewportArguments.h"
	#endif

	#if PLATFORM(COCOA)
	#import <wtf/RetainPtr.h>
	typedef struct objc_object* id;
	#endif

	namespace WebCore {

	class CachedPage;
	class Document;
	class FormData;
	class HistoryItem;
	class Image;
	class ResourceRequest;
	enum class PruningReason;

	WEBCORE_EXPORT extern void (*notifyHistoryItemChanged)(HistoryItem&);

	class HistoryItem : public RefCounted<HistoryItem> {
	friend class PageCache;

	public:
	static Ref<HistoryItem> create()
	{
	return adoptRef(*new HistoryItem);
	}

	static Ref<HistoryItem> create(const String& urlString, const String& title)
	{
	return adoptRef(*new HistoryItem(urlString, title));
	}

	static Ref<HistoryItem> create(const String& urlString, const String& title, const String& alternateTitle)
	{
	return adoptRef(*new HistoryItem(urlString, title, alternateTitle));
	}

	static Ref<HistoryItem> create(const String& urlString, const String& title, const String& alternateTitle, BackForwardItemIdentifier identifier)
	{
	return adoptRef(*new HistoryItem(urlString, title, alternateTitle, identifier));
	}

	WEBCORE_EXPORT ~HistoryItem();

	WEBCORE_EXPORT Ref<HistoryItem> copy() const;

	const BackForwardItemIdentifier& identifier() const { return m_identifier; }

	// Resets the HistoryItem to its initial state, as returned by create().
	void reset();

	WEBCORE_EXPORT const String& originalURLString() const;
	WEBCORE_EXPORT const String& urlString() const;
	WEBCORE_EXPORT const String& title() const;

	bool isInPageCache() const { return m_cachedPage.get(); }
	WEBCORE_EXPORT bool hasCachedPageExpired() const;

	WEBCORE_EXPORT void setAlternateTitle(const String&);
	WEBCORE_EXPORT const String& alternateTitle() const;

	WEBCORE_EXPORT URL url() const;
	WEBCORE_EXPORT URL originalURL() const;
	WEBCORE_EXPORT const String& referrer() const;
	WEBCORE_EXPORT const String& target() const;
	WEBCORE_EXPORT bool isTargetItem() const;

	WEBCORE_EXPORT FormData* formData();
	WEBCORE_EXPORT String formContentType() const;

	bool lastVisitWasFailure() const { return m_lastVisitWasFailure; }

	WEBCORE_EXPORT const IntPoint& scrollPosition() const;
	WEBCORE_EXPORT void setScrollPosition(const IntPoint&);
	void clearScrollPosition();

	WEBCORE_EXPORT bool shouldRestoreScrollPosition() const;
	WEBCORE_EXPORT void setShouldRestoreScrollPosition(bool);

	WEBCORE_EXPORT float pageScaleFactor() const;
	WEBCORE_EXPORT void setPageScaleFactor(float);

	WEBCORE_EXPORT const Vector<String>& documentState() const;
	WEBCORE_EXPORT void setDocumentState(const Vector<String>&);
	void clearDocumentState();

	WEBCORE_EXPORT void setShouldOpenExternalURLsPolicy(ShouldOpenExternalURLsPolicy);
	WEBCORE_EXPORT ShouldOpenExternalURLsPolicy shouldOpenExternalURLsPolicy() const;

	void setURL(const URL&);
	WEBCORE_EXPORT void setURLString(const String&);
	WEBCORE_EXPORT void setOriginalURLString(const String&);
	WEBCORE_EXPORT void setReferrer(const String&);
	WEBCORE_EXPORT void setTarget(const String&);
	WEBCORE_EXPORT void setTitle(const String&);
	WEBCORE_EXPORT void setIsTargetItem(bool);

	WEBCORE_EXPORT void setStateObject(RefPtr<SerializedScriptValue>&&);
	SerializedScriptValue* stateObject() const { return m_stateObject.get(); }

	void setItemSequenceNumber(long long number) { m_itemSequenceNumber = number; }
	long long itemSequenceNumber() const { return m_itemSequenceNumber; }

	void setDocumentSequenceNumber(long long number) { m_documentSequenceNumber = number; }
	long long documentSequenceNumber() const { return m_documentSequenceNumber; }

	void setFormInfoFromRequest(const ResourceRequest&);
	WEBCORE_EXPORT void setFormData(RefPtr<FormData>&&);
	WEBCORE_EXPORT void setFormContentType(const String&);

	void setLastVisitWasFailure(bool wasFailure) { m_lastVisitWasFailure = wasFailure; }

	WEBCORE_EXPORT void addChildItem(Ref<HistoryItem>&&);
	void setChildItem(Ref<HistoryItem>&&);
	WEBCORE_EXPORT HistoryItem* childItemWithTarget(const String&);
	HistoryItem* childItemWithDocumentSequenceNumber(long long number);
	WEBCORE_EXPORT const Vector<Ref<HistoryItem>>& children() const;
	WEBCORE_EXPORT bool hasChildren() const;
	void clearChildren();

	bool shouldDoSameDocumentNavigationTo(HistoryItem& otherItem) const;
	bool hasSameFrames(HistoryItem& otherItem) const;

	bool isCurrentDocument(Document&) const;

	#if PLATFORM(COCOA)
	WEBCORE_EXPORT id viewState() const;
	WEBCORE_EXPORT void setViewState(id);
	#endif

	#ifndef NDEBUG
	int showTree() const;
	int showTreeWithIndent(unsigned indentLevel) const;
	#endif

	#if PLATFORM(IOS_FAMILY)
	FloatRect exposedContentRect() const { return m_exposedContentRect; }
	void setExposedContentRect(FloatRect exposedContentRect) { m_exposedContentRect = exposedContentRect; }

	IntRect unobscuredContentRect() const { return m_unobscuredContentRect; }
	void setUnobscuredContentRect(IntRect unobscuredContentRect) { m_unobscuredContentRect = unobscuredContentRect; }

	const FloatBoxExtent& obscuredInsets() const { return m_obscuredInsets; }
	void setObscuredInsets(const FloatBoxExtent& insets) { m_obscuredInsets = insets; }

	FloatSize minimumLayoutSizeInScrollViewCoordinates() const { return m_minimumLayoutSizeInScrollViewCoordinates; }
	void setMinimumLayoutSizeInScrollViewCoordinates(FloatSize minimumLayoutSizeInScrollViewCoordinates) { m_minimumLayoutSizeInScrollViewCoordinates = minimumLayoutSizeInScrollViewCoordinates; }

	IntSize contentSize() const { return m_contentSize; }
	void setContentSize(IntSize contentSize) { m_contentSize = contentSize; }

	float scale() const { return m_scale; }
	bool scaleIsInitial() const { return m_scaleIsInitial; }
	void setScaleIsInitial(bool scaleIsInitial) { m_scaleIsInitial = scaleIsInitial; }
	void setScale(float newScale, bool isInitial)
	{
	m_scale = newScale;
	m_scaleIsInitial = isInitial;
	}

	const ViewportArguments& viewportArguments() const { return m_viewportArguments; }
	void setViewportArguments(const ViewportArguments& viewportArguments) { m_viewportArguments = viewportArguments; }
	#endif

	void notifyChanged();

	void setWasRestoredFromSession(bool wasRestoredFromSession) { m_wasRestoredFromSession = wasRestoredFromSession; }
	bool wasRestoredFromSession() const { return m_wasRestoredFromSession; }

	#if !LOG_DISABLED
	const char* logString() const;
	#endif

	private:
	WEBCORE_EXPORT HistoryItem();
	WEBCORE_EXPORT HistoryItem(const String& urlString, const String& title);
	WEBCORE_EXPORT HistoryItem(const String& urlString, const String& title, const String& alternateTitle);
	WEBCORE_EXPORT HistoryItem(const String& urlString, const String& title, const String& alternateTitle, BackForwardItemIdentifier);

	void setCachedPage(std::unique_ptr<CachedPage>&&);
	std::unique_ptr<CachedPage> takeCachedPage();

	HistoryItem(const HistoryItem&);

	static int64_t generateSequenceNumber();

	bool hasSameDocumentTree(HistoryItem& otherItem) const;

	String m_urlString;
	String m_originalURLString;
	String m_referrer;
	String m_target;
	String m_title;
	String m_displayTitle;

	IntPoint m_scrollPosition;
	float m_pageScaleFactor { 0 }; // 0 indicates "unset".
	Vector<String> m_documentState;

	ShouldOpenExternalURLsPolicy m_shouldOpenExternalURLsPolicy { ShouldOpenExternalURLsPolicy::ShouldNotAllow };

	Vector<Ref<HistoryItem>> m_children;

	bool m_lastVisitWasFailure { false };
	bool m_isTargetItem { false };
	bool m_wasRestoredFromSession { false };
	bool m_shouldRestoreScrollPosition { true };

	// If two HistoryItems have the same item sequence number, then they are
	// clones of one another. Traversing history from one such HistoryItem to
	// another is a no-op. HistoryItem clones are created for parent and
	// sibling frames when only a subframe navigates.
	int64_t m_itemSequenceNumber { generateSequenceNumber() };

	// If two HistoryItems have the same document sequence number, then they
	// refer to the same instance of a document. Traversing history from one
	// such HistoryItem to another preserves the document.
	int64_t m_documentSequenceNumber { generateSequenceNumber() };

	// Support for HTML5 History
	RefPtr<SerializedScriptValue> m_stateObject;

	// info used to repost form data
	RefPtr<FormData> m_formData;
	String m_formContentType;

	// PageCache controls these fields.
	std::unique_ptr<CachedPage> m_cachedPage;
	PruningReason m_pruningReason;

	#if PLATFORM(IOS_FAMILY)
	FloatRect m_exposedContentRect;
	IntRect m_unobscuredContentRect;
	FloatSize m_minimumLayoutSizeInScrollViewCoordinates;
	IntSize m_contentSize;
	FloatBoxExtent m_obscuredInsets;
	float m_scale { 0 }; // Note that UIWebView looks for a non-zero value, so this has to start as 0.
	bool m_scaleIsInitial { false };
	ViewportArguments m_viewportArguments;
	#endif

	#if PLATFORM(COCOA)
	RetainPtr<id> m_viewState;
	#endif

	BackForwardItemIdentifier m_identifier;
	};

	} // namespace WebCore

	#if ENABLE(TREE_DEBUGGING)
	// Outside the WebCore namespace for ease of invocation from the debugger.
	extern "C" int showTree(const WebCore::HistoryItem*);
	#endif