Do not change the default Z-order for a bubble when it appears for an active window.

ui/views/bubble/bubble_delegate.cc

 // Copyright (c) 2012 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 "ui/views/bubble/bubble_delegate.h"
 
 #include "ui/accessibility/ax_view_state.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/color_utils.h"
 #include "ui/gfx/geometry/rect.h"
@@ skipping 22 matching lines @@
   bubble_params.opacity = Widget::InitParams::TRANSLUCENT_WINDOW;
   bubble_params.accept_events = bubble->accept_events();
   if (bubble->parent_window())
     bubble_params.parent = bubble->parent_window();
   else if (bubble->anchor_widget())
     bubble_params.parent = bubble->anchor_widget()->GetNativeView();
   bubble_params.activatable = bubble->CanActivate() ?
       Widget::InitParams::ACTIVATABLE_YES : Widget::InitParams::ACTIVATABLE_NO;
   bubble->OnBeforeBubbleWidgetInit(&bubble_params, bubble_widget);
   bubble_widget->Init(bubble_params);
-  if (bubble_params.parent)
-    bubble_widget->StackAbove(bubble_params.parent);
+  if (bubble_params.parent) {
+    // If the parent is active, let the bubble become a top-most window.
+    // Otherwise, place it above the parent so other top level windows aren't
+    // overlapped.
+    Widget* parent = Widget::GetWidgetForNativeView(bubble_params.parent);

[sky, 2015/06/30 16:43:13]

Why do we need to special case this? Shouldn't we end up with the same result?

[vasilii, 2015/06/30 18:57:03]

The original bug http://crbug.com/486730 was that the bubble from a background
window suddenly appears in foreground. In this patch I address precisely the
case of inactive window. For the active window the stacking remains correct as
before.

[sky, 2015/06/30 22:07:54]

My question is why it matters. Won't the same thing happen if you leave the code
as it was?

[vasilii, 2015/07/01 09:29:40]

No, just watch the video from http://crbug.com/504307 that is the corresponding
bug for this CL.

[sky, 2015/07/01 16:35:17]

Sorry, but you're still not explaining why this code is needed. We always want
the bubble on top of the parent (if there is one) regardless of active status.
What is StackAbove doing wrong in the case of an inactive window?

[vasilii, 2015/07/02 09:12:52]

The user opened a profile chooser. Then he opens the zoom bubble. The code
places the bubble right above the parent and below the profile chooser which
looks strange. Instead it should be placed at the default top-most position.

+    if (parent && !parent->IsActive())
+      bubble_widget->StackAbove(bubble_params.parent);
+  }
   return bubble_widget;
 }
 
 }  // namespace
 
 // static
 const char BubbleDelegateView::kViewClassName[] = "BubbleDelegateView";
 
 BubbleDelegateView::BubbleDelegateView()
     : close_on_esc_(true),
@@ skipping 259 matching lines @@
   // http://crbug.com/474622 for details.
   if (widget == GetWidget() && visible) {
     ui::AXViewState state;
     GetAccessibleState(&state);
     if (state.role == ui::AX_ROLE_ALERT_DIALOG)
       NotifyAccessibilityEvent(ui::AX_EVENT_ALERT, true);
   }
 }
 
 }  // namespace views