Added pinch viewport offset to history item.

public/web/WebHistoryItem.h

Index: public/web/WebHistoryItem.h
diff --git a/public/web/WebHistoryItem.h b/public/web/WebHistoryItem.h
index a72d2a6bff08ddbfe5420c4d65a1e5dd514ac028..f6e781866e8f5114769ee79542d89ddd8aedfa51 100644
--- a/public/web/WebHistoryItem.h
+++ b/public/web/WebHistoryItem.h
@@ -41,6 +41,7 @@ namespace blink {
 class WebHTTPBody;
 class WebString;
 class WebSerializedScriptValue;
+struct WebFloatPoint;
 struct WebPoint;
 template <typename T> class WebVector;
 
@@ -82,6 +83,9 @@ public:
     BLINK_EXPORT WebString target() const;
     BLINK_EXPORT void setTarget(const WebString&);
 
+    BLINK_EXPORT WebFloatPoint pinchViewportScrollOffset() const;
+    BLINK_EXPORT void setPinchViewportScrollOffset(const WebFloatPoint&);
+
     BLINK_EXPORT WebPoint scrollOffset() const;
     BLINK_EXPORT void setScrollOffset(const WebPoint&);