mus: Server-side implementation of modal windows

components/mus/ws/window_tree.cc

Index: components/mus/ws/window_tree.cc
diff --git a/components/mus/ws/window_tree.cc b/components/mus/ws/window_tree.cc
index 7782e8b30fecbc69df847ec8797d0ca23621d9b2..fe82ecc8d3f91b9981a3789ca8877e8b2de395d5 100644
--- a/components/mus/ws/window_tree.cc
+++ b/components/mus/ws/window_tree.cc
@@ -223,6 +223,18 @@ bool WindowTree::AddTransientWindow(const ClientWindowId& window_id,
   return false;
 }
 
+bool WindowTree::SetAsModal(const ClientWindowId& window_id) {
+  ServerWindow* window = GetWindowByClientId(window_id);
+  if (window && access_policy_->CanSetAsModal(window)) {
+    window->SetAsModal();
+    Display* display = GetDisplay(window);
+    if (display)
+      display->ReleaseCaptureForModalWindow(window);
+    return true;
+  }
+  return false;
+}
+
 std::vector<const ServerWindow*> WindowTree::GetWindowTree(
     const ClientWindowId& window_id) const {
   const ServerWindow* window = GetWindowByClientId(window_id);
@@ -984,6 +996,10 @@ void WindowTree::RemoveTransientWindowFromParent(uint32_t change_id,
   client()->OnChangeCompleted(change_id, success);
 }
 
+void WindowTree::SetAsModal(uint32_t change_id, Id window_id) {
+  client()->OnChangeCompleted(change_id, SetAsModal(ClientWindowId(window_id)));
+}
+
 void WindowTree::ReorderWindow(uint32_t change_id,
                                Id window_id,
                                Id relative_window_id,
@@ -1021,7 +1037,7 @@ void WindowTree::SetCapture(uint32_t change_id, Id window_id) {
                  event_ack_id_;
   if (success) {
     Operation op(this, connection_manager_, OperationType::SET_CAPTURE);
-    display->SetCapture(window, !HasRoot(window));
+    success = display->SetCapture(window, !HasRoot(window));
   }
   client()->OnChangeCompleted(change_id, success);
 }
@@ -1037,7 +1053,7 @@ void WindowTree::ReleaseCapture(uint32_t change_id, Id window_id) {
                  window == current_capture_window;
   if (success) {
     Operation op(this, connection_manager_, OperationType::RELEASE_CAPTURE);
-    display->SetCapture(nullptr, false);
+    success = display->SetCapture(nullptr, false);
   }
   client()->OnChangeCompleted(change_id, success);
 }