aura-mus: create an interactive ui test for drag and drop.

ui/aura/env.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/aura/env.h"
 
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "base/memory/ptr_util.h"
 #include "base/threading/thread_local.h"
@@ skipping 58 matching lines @@
  private:
   Window* window_;
 
   DISALLOW_COPY_AND_ASSIGN(ActiveFocusClientWindowObserver);
 };
 
 ////////////////////////////////////////////////////////////////////////////////
 // Env, public:
 
 Env::~Env() {
-  if (RunningInsideMus())
+  if (is_os_exchange_data_provider_factory_)
     ui::OSExchangeDataProviderFactory::SetFactory(nullptr);
 
   for (EnvObserver& observer : observers_)
     observer.OnWillDestroyEnv();
   DCHECK_EQ(this, lazy_tls_ptr.Pointer()->Get());
   lazy_tls_ptr.Pointer()->Set(NULL);
 }
 
 // static
 std::unique_ptr<Env> Env::CreateInstance(Mode mode) {
@@ skipping 100 matching lines @@
       get_last_mouse_location_from_mus_(mode_ == Mode::MUS),
       input_state_lookup_(InputStateLookup::Create()),
       context_factory_(nullptr),
       context_factory_private_(nullptr) {
   DCHECK(lazy_tls_ptr.Pointer()->Get() == NULL);
   lazy_tls_ptr.Pointer()->Set(this);
 }
 
 void Env::Init() {
   if (RunningInsideMus()) {
-    ui::OSExchangeDataProviderFactory::SetFactory(this);
+    EnableMusOSExchangeDataProvider();
     return;
   }
 
 #if defined(USE_OZONE)
   // The ozone platform can provide its own event source. So initialize the
   // platform before creating the default event source. If running inside mus
   // let the mus process initialize ozone instead.
   ui::OzonePlatform::InitializeForUI();
 #endif
   if (!ui::PlatformEventSource::GetInstance())
     event_source_ = ui::PlatformEventSource::CreateDefault();
 }
 
+void Env::EnableMusOSExchangeDataProvider() {
+  if (!is_os_exchange_data_provider_factory_) {
+    ui::OSExchangeDataProviderFactory::SetFactory(this);
+    is_os_exchange_data_provider_factory_ = true;
+  }
+}
+
 void Env::NotifyWindowInitialized(Window* window) {
   for (EnvObserver& observer : observers_)
     observer.OnWindowInitialized(window);
 }
 
 void Env::NotifyHostInitialized(WindowTreeHost* host) {
   for (EnvObserver& observer : observers_)
     observer.OnHostInitialized(host);
 }
 
@@ skipping 24 matching lines @@
 ui::EventTargeter* Env::GetEventTargeter() {
   NOTREACHED();
   return NULL;
 }
 
 std::unique_ptr<ui::OSExchangeData::Provider> Env::BuildProvider() {
   return base::MakeUnique<aura::OSExchangeDataProviderMus>();
 }
 
 }  // namespace aura