View synchronization

mojo/services/public/cpp/view_manager/view_tree_node_observer.h

Index: mojo/services/public/cpp/view_manager/view_tree_node_observer.h
diff --git a/mojo/services/public/cpp/view_manager/view_tree_node_observer.h b/mojo/services/public/cpp/view_manager/view_tree_node_observer.h
index ac55ae6755affe5e766c1e0104383e4f0cb9efae..cd5da9d98f92b8882d3b2df0ea081dcc2609da1a 100644
--- a/mojo/services/public/cpp/view_manager/view_tree_node_observer.h
+++ b/mojo/services/public/cpp/view_manager/view_tree_node_observer.h
@@ -13,6 +13,7 @@ namespace mojo {
 namespace services {
 namespace view_manager {
 
+class View;
 class ViewTreeNode;
 
 class ViewTreeNodeObserver {
@@ -36,6 +37,11 @@ class ViewTreeNodeObserver {
   virtual void OnNodeDestroy(ViewTreeNode* node,
                              DispositionChangePhase phase) {}
 
+  virtual void OnNodeActiveViewChange(ViewTreeNode* node,
+                                      View* old_view,
+                                      View* new_view,
+                                      DispositionChangePhase phase) {}
+
  protected:
   virtual ~ViewTreeNodeObserver() {}
 };