c++ / mojo changes for 'external window mode'

services/ui/public/interfaces/window_tree_host.mojom

Index: services/ui/public/interfaces/window_tree_host.mojom
diff --git a/services/ui/public/interfaces/window_tree_host.mojom b/services/ui/public/interfaces/window_tree_host.mojom
index 8a349600a3d9b22aa5ca114ea6c949ad30e60315..aacab5e1e5a4154bab1c4c2815bf81738668393a 100644
--- a/services/ui/public/interfaces/window_tree_host.mojom
+++ b/services/ui/public/interfaces/window_tree_host.mojom
@@ -17,9 +17,32 @@ interface WindowTreeHost {
   SetTitle(string title);
 };
 
+// WindowTreeHostFactoryRegistrar is the entry point to obtain a
+// WindowTreeHostFactory instance in 'external window mode'.
+// Callers also obtain a mojo handle to the unique ws::WindowTree instance,
+// on the server-side.
+//
+// NOTE: WindowTreeHostFactoryRegistrar::Register and
+// WindowTreeHostFactory::CreatePlatformWindow are put on separate interfaces,
+// so that the interface containing ::CreatePlatformWindow is obtained by
+// calling ::Register. That eliminates the possibility of ::CreatePlatformWindow
+// being called before ::Register.
+//

[kylechar, 2017/03/07 18:19:37]

Delete empty comment line.

[tonikitoo, 2017/03/07 20:09:36]

Will fix.

+interface WindowTreeHostFactoryRegistrar {
+   Register(WindowTreeHostFactory& window_tree_host_factory,
+            WindowTree& tree_request,
+            WindowTreeClient client);
+};
+
+// WindowTreeHostFactory triggers the creation of WindowTreeHost instances.
 interface WindowTreeHostFactory {
   // Creates a new WindowTreeHost. |tree_client| is queried for the
   // WindowManager.
   CreateWindowTreeHost(WindowTreeHost& window_tree_host,
                        WindowTreeClient tree_client);
+
+  // Creates a new WindowTreeHost in 'external window mode'.
+  // One WindowTree/WindowTreeClient pair can serve one or more WindowTreeHost
+  // instances.
+  CreatePlatformWindow(WindowTreeHost& window_tree_host, uint32 client_id);

[kylechar, 2017/03/07 18:19:36]

What is |client_id| supposed to be?

[tonikitoo, 2017/03/07 20:09:36]

WindowHostTreeMus is created on the client side before its associated root
ws::ServerWindow. Since it already has an 'id', we need to inform the server
about it.
So, this client_id is the 'id' of this WindowHostTreeMus instance.

Later on, in WindowTree::AddRoot, we associated this 'id' with the respective
server window id (see below).


219 void WindowTree::AddRoot(const ServerWindow* root) {
220   DCHECK(pending_client_id_ != kInvalidClientId);
221 
222   const ClientWindowId client_window_id(pending_client_id_);
223   DCHECK_EQ(0u, client_id_to_window_id_map_.count(client_window_id));
224 
225   client_id_to_window_id_map_[client_window_id] = root->id();
226   window_id_to_client_id_map_[root->id()] = client_window_id;
227   pending_client_id_ = kInvalidClientId;
(...)      
233 }

 };