Added pinch viewport offset to history item.

Source/core/frame/PinchViewport.cpp

Index: Source/core/frame/PinchViewport.cpp
diff --git a/Source/core/frame/PinchViewport.cpp b/Source/core/frame/PinchViewport.cpp
index 505a8895eadcbeeb9a3b05a04fe97c3095d78f88..6bd8d8bbaa3da824c24869be0fa51e20c32a0876 100644
--- a/Source/core/frame/PinchViewport.cpp
+++ b/Source/core/frame/PinchViewport.cpp
@@ -91,6 +91,12 @@ void PinchViewport::setSize(const IntSize& size)
     setupScrollbar(WebScrollbar::Vertical);
 }
 
+void PinchViewport::reset()
+{
+    setLocation(FloatPoint(0, 0));
+    setScale(1);
+}
+
 void PinchViewport::mainFrameDidChangeSize()
 {
     // In unit tests we may not have initialized the layer tree.
@@ -124,8 +130,13 @@ void PinchViewport::setLocation(const FloatPoint& newLocation)
 
 void PinchViewport::setScale(float scale)
 {
+    if (scale == m_scale)
+        return;
+
     m_scale = scale;
 
+    mainFrame()->loader().saveScrollState();
+
     // Old-style pinch sets scale here but we shouldn't call into the
     // clamping code below.
     if (!m_innerViewportScrollLayer)
@@ -133,6 +144,9 @@ void PinchViewport::setScale(float scale)
 
     // Ensure we clamp so we remain within the bounds.
     setLocation(visibleRect().location());
+
+    // TODO: We should probably be calling scaleDidChange type functions here.

[aelias_OOO_until_Jul13, 2014/05/07 08:06:03]

Separate from this patch, but the only thing in you might need to call is
m_pageScaleConstraintsSet.setNeedsReset(false);  (which might come up in Android
scale initialization cases later).

+    // see Page::setPageScaleFactor.
 }
 
 // Modifies the top of the graphics layer tree to add layers needed to support
@@ -324,6 +338,8 @@ void PinchViewport::invalidateScrollbarRect(Scrollbar*, const IntRect&)
 void PinchViewport::setScrollOffset(const IntPoint& offset)
 {
     setLocation(offset);
+
+    mainFrame()->loader().saveScrollState();
 }
 
 GraphicsLayer* PinchViewport::layerForContainer() const