Moves TransientWindowClient to ui/aura/client and adds observer

ui/wm/test/wm_test_helper.cc

 // Copyright 2013 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/wm/test/wm_test_helper.h"
 
+#include "base/memory/ptr_util.h"
 #include "ui/aura/client/default_capture_client.h"
 #include "ui/aura/env.h"
 #include "ui/aura/test/input_method_glue.h"
 #include "ui/aura/test/test_focus_client.h"
 #include "ui/aura/window.h"
 #include "ui/wm/core/compound_event_filter.h"
 #include "ui/wm/core/default_activation_client.h"
+#include "ui/wm/core/wm_state.h"
 
 namespace wm {
 
 WMTestHelper::WMTestHelper(const gfx::Size& default_window_size,
                            ui::ContextFactory* context_factory) {
+  wm_state_ = base::MakeUnique<WMState>();
   aura::Env::GetInstance()->set_context_factory(context_factory);
   host_.reset(aura::WindowTreeHost::Create(gfx::Rect(default_window_size)));
   host_->InitHost();
   input_method_glue_.reset(new aura::InputMethodGlue(host_.get()));
   aura::client::SetWindowParentingClient(host_->window(), this);
 
   focus_client_.reset(new aura::test::TestFocusClient);
   aura::client::SetFocusClient(host_->window(), focus_client_.get());
 
   root_window_event_filter_.reset(new wm::CompoundEventFilter);
   host_->window()->AddPreTargetHandler(root_window_event_filter_.get());
 
   new wm::DefaultActivationClient(host_->window());
 
   capture_client_.reset(
       new aura::client::DefaultCaptureClient(host_->window()));
 }
 
 WMTestHelper::~WMTestHelper() {
 }
 
 aura::Window* WMTestHelper::GetDefaultParent(aura::Window* context,
                                              aura::Window* window,
                                              const gfx::Rect& bounds) {
   return host_->window();
 }
 
 }  // namespace wm