Add a setNeedsLayout method to WebPluginContainer.

public/web/WebPluginContainer.h

Index: public/web/WebPluginContainer.h
diff --git a/public/web/WebPluginContainer.h b/public/web/WebPluginContainer.h
index 93026d0a25e5be5240fb9f85dddefeb4e5bfe268..aaaaef4c63e6295f0179b8f36901319a090092d2 100644
--- a/public/web/WebPluginContainer.h
+++ b/public/web/WebPluginContainer.h
@@ -63,6 +63,12 @@ public:
     virtual void invalidateRect(const WebRect&) = 0;
     virtual void scrollRect(const WebRect&) = 0;
 
+    // Causes the container to be marked as needing layout, which in turn will cause
+    // layoutIfNeeded() to be called on any contained WebPlugin during the container's
+    // web view's lifecycle update, and in particular before calling paint() on the
+    // WebPlugin.
+    virtual void setNeedsLayout() = 0;
+
     // Causes the container to report its current geometry via
     // WebPlugin::updateGeometry.
     virtual void reportGeometry() = 0;