Do not give instant focus if a view's toplevelwidget is not active

ui/views/mus/native_widget_mus.cc

 // Copyright 2015 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.
 
 // This has to be before any other includes, else default is picked up.
 // See base/logging for details on this.
 #define NOTIMPLEMENTED_POLICY 5
 
 #include "ui/views/mus/native_widget_mus.h"
 
@@ skipping 1077 matching lines @@
   if (state == ui::SHOW_STATE_MINIMIZED)
     Minimize();
 }
 
 bool NativeWidgetMus::IsVisible() const {
   // TODO(beng): this should probably be wired thru PlatformWindow.
   return window_ && window_->visible();
 }
 
 void NativeWidgetMus::Activate() {
+  if (!window_)
+    return;
+
   static_cast<aura::client::ActivationClient*>(focus_client_.get())
       ->ActivateWindow(content_);
-  // FocusControllerMus should have focused |window_| when |content_| is
-  // activated.
-  DCHECK(!window_ || window_->HasFocus());
 }
 
 void NativeWidgetMus::Deactivate() {
   if (IsActive())
     window_->window_tree()->ClearFocus();
 }
 
 bool NativeWidgetMus::IsActive() const {
   ui::Window* focused =
       window_ ? window_->window_tree()->GetFocusedWindow() : nullptr;
@@ skipping 423 matching lines @@
 
   gfx::Path mask_path;
   native_widget_delegate_->GetHitTestMask(&mask_path);
   // TODO(jamescook): Use the full path for the mask.
   gfx::Rect mask_rect =
       gfx::ToEnclosingRect(gfx::SkRectToRectF(mask_path.getBounds()));
   window_->SetHitTestMask(mask_rect);
 }
 
 }  // namespace views