A window should not get activated or get input focus if it's behind the lock screen.

ui/views/widget/native_widget_aura.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/widget/native_widget_aura.h"
 
 #include "base/bind.h"
 #include "base/strings/string_util.h"
 #include "build/build_config.h"
 #include "third_party/skia/include/core/SkRegion.h"
@@ skipping 471 matching lines @@
 
 void NativeWidgetAura::ShowWithWindowState(ui::WindowShowState state) {
   if (!window_)
     return;
 
   if (state == ui::SHOW_STATE_MAXIMIZED || state == ui::SHOW_STATE_FULLSCREEN ||
       state == ui::SHOW_STATE_DOCKED) {
     window_->SetProperty(aura::client::kShowStateKey, state);
   }
   window_->Show();
-  if (delegate_->CanActivate()) {
+  if (delegate_->CanActivate() && wm::CanActivateWindow(window_)) {

[sky, 2016/03/03 20:22:47]

I think this is the wrong place for the fix. If you call Activate() and the
window isn't active, then the FocusController should ignore the activate
request.

[xdai1, 2016/03/03 22:01:31]

You're right. Since the goal is to prevent SetInitalFocus() from being called,
so maybe I should move this one line fix below?

[sky, 2016/03/03 23:39:33]

What is SetInitialFocus doing that is wrong? I think what should happen is if
Activate fails then you supply ui::SHOW_STATE_INACTIVE to SetInitialFocus. But I
could be misunderstanding the bug.

     if (state != ui::SHOW_STATE_INACTIVE)
       Activate();
     // SetInitialFocus() should be always be called, even for
     // SHOW_STATE_INACTIVE. If the window has to stay inactive, the method will
     // do the right thing.
     SetInitialFocus(state);
   }
 
   // On desktop aura, a window is activated first even when it is shown as
   // minimized. Do the same for consistency.
@@ skipping 664 matching lines @@
   l10n_util::AdjustUIFont(&(ncm.lfCaptionFont));
   base::win::ScopedHFONT caption_font(CreateFontIndirect(&(ncm.lfCaptionFont)));
   return gfx::FontList(gfx::Font(caption_font.get()));
 #else
   return gfx::FontList();
 #endif
 }
 
 }  // namespace internal
 }  // namespace views