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 33dc0e360574e055e8dc0a40af63bee4edc84ae5..a35f6eb853562371710b88fe98b74c91b4d534c2 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&);