[views] Makes DesktopWindowTreeHostX11::FrameTypeChanged use PostTask

ui/views/widget/desktop_aura/desktop_window_tree_host_x11.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/desktop_aura/desktop_window_tree_host_x11.h"
 
 #include <X11/extensions/shape.h>
 #include <X11/extensions/XInput2.h>
 #include <X11/Xatom.h>
 #include <X11/Xregion.h>
@@ skipping 1009 matching lines @@
 }
 
 void DesktopWindowTreeHostX11::FrameTypeChanged() {
   Widget::FrameType new_type =
       native_widget_delegate_->AsWidget()->frame_type();
   if (new_type == Widget::FRAME_TYPE_DEFAULT) {
     // The default is determined by Widget::InitParams::remove_standard_frame
     // and does not change.
     return;
   }
-
-  SetUseNativeFrame(new_type == Widget::FRAME_TYPE_FORCE_NATIVE);
-  // Replace the frame and layout the contents. Even though we don't have a
-  // swapable glass frame like on Windows, we still replace the frame because
-  // the button assets don't update otherwise.
-  native_widget_delegate_->AsWidget()->non_client_view()->UpdateFrame();
+  // Avoid mutating |View::children_| while possibly iterating over them.
+  // See View::PropagateNativeThemeChanged().
+  // TODO(varkha, sadrul): Investigate removing this (and instead expecting the
+  // NonClientView::UpdateFrame() to update the frame-view when theme changes,
+  // like all other views).
+  base::ThreadTaskRunnerHandle::Get()->PostTask(
+      FROM_HERE, base::Bind(&DesktopWindowTreeHostX11::DelayedChangeFrameType,
+                            weak_factory_.GetWeakPtr(),
+                            new_type));
 }
 
 void DesktopWindowTreeHostX11::SetFullscreen(bool fullscreen) {
   if (is_fullscreen_ == fullscreen)
     return;
   is_fullscreen_ = fullscreen;
   if (is_fullscreen_)
     delayed_resize_task_.Cancel();
 
   // Work around a bug where if we try to unfullscreen, metacity immediately
@@ skipping 1226 matching lines @@
   }
   return ui::POST_DISPATCH_STOP_PROPAGATION;
 }
 
 void DesktopWindowTreeHostX11::DelayedResize(const gfx::Size& size_in_pixels) {
   OnHostResizedInPixels(size_in_pixels);
   ResetWindowRegion();
   delayed_resize_task_.Cancel();
 }
 
+void DesktopWindowTreeHostX11::DelayedChangeFrameType(Widget::FrameType type) {
+  SetUseNativeFrame(type == Widget::FRAME_TYPE_FORCE_NATIVE);
+  // Replace the frame and layout the contents. Even though we don't have a
+  // swappable glass frame like on Windows, we still replace the frame because
+  // the button assets don't update otherwise.
+  native_widget_delegate_->AsWidget()->non_client_view()->UpdateFrame();
+}
+
 gfx::Rect DesktopWindowTreeHostX11::GetWorkAreaBoundsInPixels() const {
   std::vector<int> value;
   if (ui::GetIntArrayProperty(x_root_window_, "_NET_WORKAREA", &value) &&
       value.size() >= 4) {
     return gfx::Rect(value[0], value[1], value[2], value[3]);
   }
 
   // Fetch the geometry of the root window.
   Window root;
   int x, y;
@@ skipping 52 matching lines @@
 
 // static
 DesktopWindowTreeHost* DesktopWindowTreeHost::Create(
     internal::NativeWidgetDelegate* native_widget_delegate,
     DesktopNativeWidgetAura* desktop_native_widget_aura) {
   return new DesktopWindowTreeHostX11(native_widget_delegate,
                                       desktop_native_widget_aura);
 }
 
 }  // namespace views