aura-mus: Implement DesktopWindowTreeHostMus::StackAbove().

services/ui/ws/window_tree.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "services/ui/ws/window_tree.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 1264 matching lines @@
 }
 
 void WindowTree::SetModal(uint32_t change_id, Id window_id) {
   client()->OnChangeCompleted(change_id, SetModal(ClientWindowId(window_id)));
 }
 
 void WindowTree::ReorderWindow(uint32_t change_id,
                                Id window_id,
                                Id relative_window_id,
                                mojom::OrderDirection direction) {
+  // TODO(erg): This implementation allows reordering two windows that are
+  // children of a parent window which the two implementations can't see. There
+  // should be a security check to prevent this.
   bool success = false;
   ServerWindow* window = GetWindowByClientId(ClientWindowId(window_id));
   ServerWindow* relative_window =
       GetWindowByClientId(ClientWindowId(relative_window_id));
   DVLOG(3) << "reorder client=" << id_ << " client window_id=" << window_id
            << " global window_id="
            << (window ? WindowIdToTransportId(window->id()) : 0)
            << " relative client window_id=" << relative_window_id
            << " relative global window_id="
            << (relative_window ? WindowIdToTransportId(relative_window->id())
@@ skipping 294 matching lines @@
     // The window isn't parented. There's nothing to do.
     DVLOG(1) << "DeactivateWindow failed (window unparented)";
     return;
   }
 
   WindowTree* wm_tree = display_root->window_manager_state()->window_tree();
   wm_tree->window_manager_internal_->WmDeactivateWindow(
       wm_tree->ClientWindowIdForWindow(window).id);
 }
 
+void WindowTree::StackAbove(uint32_t change_id, Id above_id, Id below_id) {
+  ServerWindow* above = GetWindowByClientId(ClientWindowId(above_id));
+  if (!above) {
+    DVLOG(1) << "StackAtTop failed (invalid above id)";
+    client()->OnChangeCompleted(change_id, false);
+    return;
+  }
+
+  ServerWindow* below = GetWindowByClientId(ClientWindowId(below_id));
+  if (!below) {
+    DVLOG(1) << "StackAtTop failed (invalid below id)";
+    client()->OnChangeCompleted(change_id, false);
+    return;
+  }
+
+  if (!access_policy_->CanStackAbove(above, below)) {
+    DVLOG(1) << "StackAtTop failed (access denied)";
+    client()->OnChangeCompleted(change_id, false);
+    return;
+  }
+
+  ServerWindow* parent = above->parent();
+  ServerWindow* below_parent = below->parent();
+  if (!parent) {
+    DVLOG(1) << "StackAtTop failed (above unparented)";
+    client()->OnChangeCompleted(change_id, false);
+    return;
+  }
+  if (!below_parent) {
+    DVLOG(1) << "StackAtTop failed (below unparented)";
+    client()->OnChangeCompleted(change_id, false);
+    return;
+  }
+  if (parent != below_parent) {
+    DVLOG(1) << "StackAtTop failed (windows have different parents)";
+    client()->OnChangeCompleted(change_id, false);
+    return;
+  }
+
+  WindowManagerDisplayRoot* display_root = GetWindowManagerDisplayRoot(above);
+  if (!display_root) {
+    DVLOG(1) << "StackAtTop (no display root)";
+    client()->OnChangeCompleted(change_id, false);
+    return;
+  }
+
+  // Window reordering assumes that it is the owner of parent who is sending
+  // the message, and does not deal gracefully with other clients reordering
+  // their windows. So tell the window manager to send us a reorder message.
+  WindowTree* wm_tree = display_root->window_manager_state()->window_tree();
+  const uint32_t wm_change_id =
+      window_server_->GenerateWindowManagerChangeId(this, change_id);
+  wm_tree->window_manager_internal_->WmStackAbove(
+      wm_change_id,
+      wm_tree->ClientWindowIdForWindow(above).id,
+      wm_tree->ClientWindowIdForWindow(below).id);
+}
+
 void WindowTree::StackAtTop(uint32_t change_id, Id window_id) {
   ServerWindow* window = GetWindowByClientId(ClientWindowId(window_id));
   if (!window) {
     DVLOG(1) << "StackAtTop failed (invalid id)";
     client()->OnChangeCompleted(change_id, false);
     return;
   }
 
   if (!access_policy_->CanStackAtTop(window)) {
     DVLOG(1) << "StackAtTop failed (access denied)";
@@ skipping 471 matching lines @@
   client()->OnCompleteDrop(client_window_id.id, event_flags, cursor_offset,
                            effect_bitmask, callback);
 }
 
 void WindowTree::PerformOnDragDropDone() {
   client()->OnDragDropDone();
 }
 
 }  // namespace ws
 }  // namespace ui