aura: No shadow for transparent window.

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/string_util.h"
 #include "ui/aura/client/activation_client.h"
 #include "ui/aura/client/aura_constants.h"
@@ skipping 148 matching lines @@
 // NativeWidgetAura, internal::NativeWidgetPrivate implementation:
 
 void NativeWidgetAura::InitNativeWidget(const Widget::InitParams& params) {
   ownership_ = params.ownership;
   window_->set_user_data(this);
   Widget::InitParams::Type window_type =
       params.child ? Widget::InitParams::TYPE_CONTROL : params.type;
   window_->SetType(GetAuraWindowTypeForWidgetType(window_type));
   // TODO(jamescook): Should this use params.show_state instead?
   window_->SetIntProperty(aura::client::kShowStateKey, ui::SHOW_STATE_NORMAL);
+  window_->SetTransparent(params.transparent);
   window_->Init(params.create_texture_for_layer ?
                     ui::Layer::LAYER_HAS_TEXTURE :
                     ui::Layer::LAYER_HAS_NO_TEXTURE);
   if (window_type == Widget::InitParams::TYPE_CONTROL)
     window_->Show();
 
-  window_->layer()->SetFillsBoundsOpaquely(!params.transparent);
   delegate_->OnNativeWidgetCreated();
   window_->SetBounds(params.bounds);
   if (window_type == Widget::InitParams::TYPE_CONTROL) {
     window_->SetParent(params.GetParent());
   } else {
     // Set up the transient child before the window is added. This way the
     // LayoutManager knows the window has a transient parent.
     gfx::NativeView parent = params.GetParent();
     if (parent && parent->type() != aura::client::WINDOW_TYPE_UNKNOWN) {
       parent->AddTransientChild(window_);
@@ skipping 690 matching lines @@
   }
 }
 
 // static
 bool NativeWidgetPrivate::IsMouseButtonDown() {
   return aura::RootWindow::GetInstance()->IsMouseButtonDown();
 }
 
 }  // namespace internal
 }  // namespace views