Raise the loading priority of in-viewport images.

Source/core/rendering/RenderObject.h

Index: Source/core/rendering/RenderObject.h
diff --git a/Source/core/rendering/RenderObject.h b/Source/core/rendering/RenderObject.h
index 0866798eef11bccc7da242801911834198ce9647..b2220c946feb0340ad5a81471394d70981fc2542 100644
--- a/Source/core/rendering/RenderObject.h
+++ b/Source/core/rendering/RenderObject.h
@@ -67,6 +67,7 @@ class RenderSVGResourceContainer;
 class RenderTable;
 class RenderTheme;
 class RenderView;
+class ResourceLoadPriorityOptimizer;
 class TransformState;
 
 struct PaintInfo;
@@ -673,6 +674,8 @@ public:
 
     // Recursive function that computes the size and position of this object and all its descendants.
     virtual void layout();
+    virtual void didLayout(ResourceLoadPriorityOptimizer&);
+    virtual void didScroll(ResourceLoadPriorityOptimizer&);
 
     /* This function performs a layout only if one is needed. */
     void layoutIfNeeded() { if (needsLayout()) layout(); }