fws: Support relative ordering for window stacking

Add support for relative window ordering based on existing order
when saved as templates when launching on top of current
windows.

BUG=b:296619806
TEST=FloatingWorkspaceTest, manually verified.

Change-Id: I3141ac6447a98db75b052f84d14aad65b6038895
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4793782
Reviewed-by: Daniel Andersson <dandersson@chromium.org>
Reviewed-by: Yanzhu Du <yzd@google.com>
Commit-Queue: Matthew Zhu <zhumatthew@google.com>
Cr-Commit-Position: refs/heads/main@{#1185447}

ash/wm/desks/templates/saved_desk_util.cc

@@ -128,5 +128,26 @@ void UpdateTemplateActivationIndices(DeskTemplate& saved_desk) {
   }
 }
 
+void UpdateTemplateActivationIndicesRelativeOrder(DeskTemplate& saved_desk) {
+  auto& app_id_to_launch_list =
+      saved_desk.mutable_desk_restore_data()->mutable_app_id_to_launch_list();
+  std::vector<app_restore::AppRestoreData*> relative_window_stack_order;
+  for (auto& [app_id, launch_list] : app_id_to_launch_list) {
+    for (auto& [window_id, app_restore_data] : launch_list) {
+      relative_window_stack_order.push_back(app_restore_data.get());
+    }
+  }
+  // Sort in descending order so that we maintain the relative window
+  // stacking order.
+  base::ranges::sort(relative_window_stack_order,
+                     [](auto* window1, auto* window2) {
+                       return window1->activation_index.value_or(0) >
+                              window2->activation_index.value_or(0);
+                     });
+  for (auto* app_restore_data : relative_window_stack_order) {
+    app_restore_data->activation_index = g_template_next_activation_index--;
+  }
+}
+
 }  // namespace saved_desk_util
 }  // namespace ash

ash/wm/desks/templates/saved_desk_util.h

@@ -49,6 +49,13 @@ bool IsWindowOnTopForTemplate(aura::Window* window);
 // defined, while also stacking on top of any existing windows.
 ASH_EXPORT void UpdateTemplateActivationIndices(DeskTemplate& saved_desk);
 
+// This function updates the activation indices of all the windows in a
+// template so that windows launched from it will stack in the order that they
+// were stacked upon saving as a template, while also stacking on top of any
+// existing windows.
+ASH_EXPORT void UpdateTemplateActivationIndicesRelativeOrder(
+    DeskTemplate& saved_desk);
+
 }  // namespace saved_desk_util
 }  // namespace ash
 

chrome/browser/ash/floating_workspace/floating_workspace_service.cc

@@ -507,7 +507,7 @@ void FloatingWorkspaceService::LaunchFloatingWorkspaceTemplate(
   VLOG(1) << "Combining Floating Workspace apps to current desk.";
   std::unique_ptr<DeskTemplate> template_copy = desk_template->Clone();
   // Open the apps from the floating workspace on top of existing windows.
-  saved_desk_util::UpdateTemplateActivationIndices(*template_copy);
+  saved_desk_util::UpdateTemplateActivationIndicesRelativeOrder(*template_copy);
   GetDesksClient()->LaunchAppsFromTemplate(std::move(template_copy));
   RecordLaunchSavedDeskHistogram(DeskTemplateType::kFloatingWorkspace);
 }