Update view_manager and window_manager to make use of content handling.

mojo/services/view_manager/view_manager_service_impl.cc

Index: mojo/services/view_manager/view_manager_service_impl.cc
diff --git a/mojo/services/view_manager/view_manager_service_impl.cc b/mojo/services/view_manager/view_manager_service_impl.cc
index 69495c5f50fe5e7a522768f8852319b71e131469..282cab3a272335d1fa1fc9cf2029192f6365eb36 100644
--- a/mojo/services/view_manager/view_manager_service_impl.cc
+++ b/mojo/services/view_manager/view_manager_service_impl.cc
@@ -464,33 +464,25 @@ void ViewManagerServiceImpl::Embed(
     return;
   }
   const ServerView* view = GetView(ViewIdFromTransportId(transport_view_id));
-  bool success = view && access_policy_->CanEmbed(view);
-  if (success) {
-    // Only allow a view to be the root for one connection.
-    const ViewId view_id(ViewIdFromTransportId(transport_view_id));
-    ViewManagerServiceImpl* connection_by_url =
-        connection_manager_->GetConnectionByCreator(id_, url.To<std::string>());
-    ViewManagerServiceImpl* connection_with_view_as_root =
-        connection_manager_->GetConnectionWithRoot(view_id);
-    if ((connection_by_url != connection_with_view_as_root ||
-         (!connection_by_url && !connection_with_view_as_root)) &&
-        (!connection_by_url || !connection_by_url->HasRoot(view_id))) {
-      ConnectionManager::ScopedChange change(this, connection_manager_, true);
-      RemoveChildrenAsPartOfEmbed(view_id);
-      // Never message the originating connection.
-      connection_manager_->OnConnectionMessagedClient(id_);
-      if (connection_with_view_as_root)
-        connection_with_view_as_root->RemoveRoot(view_id);

[sky, 2014/09/02 15:47:16]

You should be able to get rid of AddRoot now.
Also, I believe you can 

[Aaron Boodman, 2014/09/02 19:10:44]

Done.

-      if (connection_by_url) {
-        connection_by_url->AddRoot(view_id, spir.Pass());
-      } else {
-        connection_manager_->Embed(id_, url, transport_view_id, spir.Pass());
-      }
-    } else {
-      success = false;
-    }
+  if (!view && access_policy_->CanEmbed(view)) {

[sky, 2014/09/02 15:47:15]

Shouldn't this be:

if (!view || !...CanEmbed(view)) ?

[Aaron Boodman, 2014/09/02 19:10:44]

Done.

+    callback.Run(false);
+    return;
   }
-  callback.Run(success);
+
+  // Only allow a node to be the root for one connection.

[Ben Goodger (Google), 2014/09/02 20:50:14]

I think this is a good simplification. I will ponder the implications on access
policy. We had been using the connection to track view visibility. I think it
was imperfect anyway since different embed chains would result in unique
connections. I think at the very least what you are doing here makes it more
consistent. 

+  const ViewId view_id(ViewIdFromTransportId(transport_view_id));
+  ViewManagerServiceImpl* existing_owner =
+      connection_manager_->GetConnectionWithRoot(view_id);
+
+  ConnectionManager::ScopedChange change(this, connection_manager_, true);
+  if (existing_owner) {
+    RemoveChildrenAsPartOfEmbed(view_id);
+    // Never message the originating connection.
+    connection_manager_->OnConnectionMessagedClient(id_);
+    existing_owner->RemoveRoot(view_id);
+  }
+  connection_manager_->Embed(id_, url, transport_view_id, spir.Pass());
+  callback.Run(true);
 }
 
 void ViewManagerServiceImpl::DispatchOnViewInputEvent(Id transport_view_id,