views/mus: Have explicit ownership of views::WindowManagerConnection.

ui/views/mus/window_manager_connection.cc

Index: ui/views/mus/window_manager_connection.cc
diff --git a/ui/views/mus/window_manager_connection.cc b/ui/views/mus/window_manager_connection.cc
index 9924b2d56fed2024a57e2a4fb4968fc21991a6ca..743c2d0260743e26ec005a57f576836374da6103 100644
--- a/ui/views/mus/window_manager_connection.cc
+++ b/ui/views/mus/window_manager_connection.cc
@@ -35,10 +35,14 @@ base::LazyInstance<WindowManagerConnectionPtr>::Leaky lazy_tls_ptr =
 }  // namespace
 
 // static
-void WindowManagerConnection::Create(shell::Connector* connector,
-                                     const shell::Identity& identity) {
+std::unique_ptr<WindowManagerConnection> WindowManagerConnection::Create(
+    shell::Connector* connector,
+    const shell::Identity& identity) {
   DCHECK(!lazy_tls_ptr.Pointer()->Get());
-  lazy_tls_ptr.Pointer()->Set(new WindowManagerConnection(connector, identity));
+  WindowManagerConnection* connection =
+      new WindowManagerConnection(connector, identity);
+  DCHECK(lazy_tls_ptr.Pointer()->Get());
+  return base::WrapUnique(connection);
 }
 
 // static
@@ -53,12 +57,6 @@ bool WindowManagerConnection::Exists() {
   return !!lazy_tls_ptr.Pointer()->Get();
 }
 
-// static
-void WindowManagerConnection::Reset() {
-  delete Get();
-  lazy_tls_ptr.Pointer()->Set(nullptr);
-}
-
 mus::Window* WindowManagerConnection::NewWindow(
     const std::map<std::string, std::vector<uint8_t>>& properties) {
   return window_tree_connection_->NewTopLevelWindow(&properties);
@@ -102,17 +100,21 @@ WindowManagerConnection::WindowManagerConnection(
     const shell::Identity& identity)
     : connector_(connector),
       identity_(identity),
-      window_tree_connection_(nullptr) {
+      created_device_data_manager_(false) {
+  lazy_tls_ptr.Pointer()->Set(this);
   window_tree_connection_.reset(
       mus::WindowTreeConnection::Create(this, connector_));
 
   screen_.reset(new ScreenMus(this));
   screen_->Init(connector);
 
-  // TODO(sad): We should have a DeviceDataManager implementation that talks to
-  // a mojo service to learn about the input-devices on the system.
-  // http://crbug.com/601981
-  ui::DeviceDataManager::CreateInstance();
+  if (!ui::DeviceDataManager::HasInstance()) {
+    // TODO(sad): We should have a DeviceDataManager implementation that talks
+    // to a mojo service to learn about the input-devices on the system.
+    // http://crbug.com/601981
+    ui::DeviceDataManager::CreateInstance();
+    created_device_data_manager_ = true;
+  }
 
   ViewsDelegate::GetInstance()->set_native_widget_factory(base::Bind(
       &WindowManagerConnection::CreateNativeWidgetMus,
@@ -124,8 +126,9 @@ WindowManagerConnection::~WindowManagerConnection() {
   // ~WindowTreeConnection calls back to us (we're the WindowTreeDelegate),
   // destroy it while we are still valid.
   window_tree_connection_.reset();
-
-  ui::DeviceDataManager::DeleteInstance();
+  if (created_device_data_manager_)
+    ui::DeviceDataManager::DeleteInstance();
+  lazy_tls_ptr.Pointer()->Set(nullptr);
 }
 
 bool WindowManagerConnection::HasPointerWatcher() {