Add support for multiple roots to the client lib.

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

Index: mojo/services/public/cpp/view_manager/view_tree_node.h
diff --git a/mojo/services/public/cpp/view_manager/view_tree_node.h b/mojo/services/public/cpp/view_manager/view_tree_node.h
index a5d9b360fc3fac17e7c338a852210c1ec325481a..913a354fb1093d416912e8955779b6a8d5671b35 100644
--- a/mojo/services/public/cpp/view_manager/view_tree_node.h
+++ b/mojo/services/public/cpp/view_manager/view_tree_node.h
@@ -9,6 +9,7 @@
 
 #include "base/basictypes.h"
 #include "base/observer_list.h"
+#include "mojo/public/cpp/bindings/array.h"
 #include "mojo/services/public/cpp/view_manager/view_manager_types.h"
 #include "ui/gfx/geometry/rect.h"
 
@@ -59,6 +60,9 @@ class ViewTreeNode {
   void SetActiveView(View* view);
   View* active_view() { return active_view_; }
 
+  // Embedding.
+  void Embed(const String& url);
+
  protected:
   // This class is subclassed only by test classes that provide a public ctor.
   ViewTreeNode();