Add pixel readback to page popup

public/web/WebWidget.h

Index: public/web/WebWidget.h
diff --git a/public/web/WebWidget.h b/public/web/WebWidget.h
index d0e12437890840de7d3f096cb11941719c0c1f65..ab1547cb006145193468567db2d49736b1e09905 100644
--- a/public/web/WebWidget.h
+++ b/public/web/WebWidget.h
@@ -50,6 +50,7 @@ class WebString;
 struct WebPoint;
 struct WebRenderingStats;
 template <typename T> class WebVector;
+class WebPagePopup;
 
 class WebWidget {
 public:
@@ -249,6 +250,9 @@ public:
     // content.
     virtual WebColor backgroundColor() const { return 0xFFFFFFFF; /* SK_ColorWHITE */ }
 
+    // The currently open popup.
+    virtual WebPagePopup* popup() const { return 0; }
+
 protected:
     ~WebWidget() { }
 };