Revert "views: random cleanup from removing support for mus"

This reverts commit f19a4c81.

Reason for revert:

Breaks https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/linux-chromeos-dbg

Sample failure line:
[ RUN      ] AppMenuModelTest.Basics
[31511:31511:0513/150125.044037:3461088700:FATAL:window.cc(91)] Check failed: env || !g_env_arg_required_string. Within ash you must supply a non-null aura::Env when creating a Window, use window_factory, or supply the Env obtained from Shell::Get()->aura_env()

Causes ~1000 tests to fail.

Original change's description:
> views: random cleanup from removing support for mus
> 
> This functionality was added purely for mus and is no longer necessary.
> 
> BUG=958241
> TEST=purely dead code removal
> 
> Change-Id: I856576f9adef9728d837d56e82f94a87aeea040b
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610497
> Commit-Queue: Scott Violet <sky@chromium.org>
> Reviewed-by: Evan Stade <estade@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#659207}

TBR=sky@chromium.org,estade@chromium.org

Change-Id: I7bbf97863986000679890e2076dbb2b0e5fdaf46
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 958241
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1610709Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Avi Drissman <avi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#659498}

ui/views/views_delegate.h

@@ -40,6 +40,8 @@ class NonClientFrameView;
 class Widget;
 
 #if defined(USE_AURA)
+class DesktopNativeWidgetAura;
+class DesktopWindowTreeHost;
 class TouchSelectionMenuRunnerViews;
 #endif
 
@@ -58,6 +60,14 @@ class VIEWS_EXPORT ViewsDelegate {
   using NativeWidgetFactory =
       base::RepeatingCallback<NativeWidget*(const Widget::InitParams&,
                                             internal::NativeWidgetDelegate*)>;
+#if defined(USE_AURA)
+  using DesktopWindowTreeHostFactory =
+      base::RepeatingCallback<std::unique_ptr<DesktopWindowTreeHost>(
+          const Widget::InitParams&,
+          internal::NativeWidgetDelegate*,
+          DesktopNativeWidgetAura*)>;
+#endif
+
 #if defined(OS_WIN)
   enum AppbarAutohideEdge {
     EDGE_TOP    = 1 << 0,
@@ -93,6 +103,15 @@ class VIEWS_EXPORT ViewsDelegate {
     return native_widget_factory_;
   }
 
+#if defined(USE_AURA)
+  void set_desktop_window_tree_host_factory(
+      DesktopWindowTreeHostFactory factory) {
+    desktop_window_tree_host_factory_ = std::move(factory);
+  }
+  const DesktopWindowTreeHostFactory& desktop_window_tree_host_factory() const {
+    return desktop_window_tree_host_factory_;
+  }
+#endif
   // Saves the position, size and "show" state for the window with the
   // specified name.
   virtual void SaveWindowPlacement(const Widget* widget,
@@ -191,6 +210,8 @@ class VIEWS_EXPORT ViewsDelegate {
 
 #if defined(USE_AURA)
   std::unique_ptr<TouchSelectionMenuRunnerViews> touch_selection_menu_runner_;
+
+  DesktopWindowTreeHostFactory desktop_window_tree_host_factory_;
 #endif
 
   NativeWidgetFactory native_widget_factory_;

ui/views/widget/desktop_aura/desktop_native_widget_aura.cc

@@ -447,6 +447,14 @@ void DesktopNativeWidgetAura::InitNativeWidget(
   if (!desktop_window_tree_host_) {
     if (params.desktop_window_tree_host) {
       desktop_window_tree_host_ = params.desktop_window_tree_host;
+    } else if (!ViewsDelegate::GetInstance()
+                    ->desktop_window_tree_host_factory()
+                    .is_null()) {
+      desktop_window_tree_host_ =
+          ViewsDelegate::GetInstance()
+              ->desktop_window_tree_host_factory()
+              .Run(params, native_widget_delegate_, this)
+              .release();
     } else {
       desktop_window_tree_host_ =
           DesktopWindowTreeHost::Create(native_widget_delegate_, this);

ui/views/widget/native_widget_aura.cc

@@ -102,9 +102,13 @@ void SetIcon(aura::Window* window,
 ////////////////////////////////////////////////////////////////////////////////
 // NativeWidgetAura, public:
 
-NativeWidgetAura::NativeWidgetAura(internal::NativeWidgetDelegate* delegate)
+NativeWidgetAura::NativeWidgetAura(internal::NativeWidgetDelegate* delegate,
+                                   bool is_parallel_widget_in_window_manager,
+                                   aura::Env* env)
     : delegate_(delegate),
-      window_(new aura::Window(this, aura::client::WINDOW_TYPE_UNKNOWN)),
+      is_parallel_widget_in_window_manager_(
+          is_parallel_widget_in_window_manager),
+      window_(new aura::Window(this, aura::client::WINDOW_TYPE_UNKNOWN, env)),
       ownership_(Widget::InitParams::NATIVE_WIDGET_OWNS_WIDGET),
       destroying_(false),
       cursor_(gfx::kNullCursor),
@@ -353,7 +357,7 @@ ui::InputMethod* NativeWidgetAura::GetInputMethod() {
 }
 
 void NativeWidgetAura::CenterWindow(const gfx::Size& size) {
-  if (!window_)
+  if (!window_ || is_parallel_widget_in_window_manager_)
     return;
 
   window_->SetProperty(aura::client::kPreferredSize, new gfx::Size(size));
@@ -415,7 +419,7 @@ void NativeWidgetAura::GetWindowPlacement(
 }
 
 bool NativeWidgetAura::SetWindowTitle(const base::string16& title) {
-  if (!window_)
+  if (!window_ || is_parallel_widget_in_window_manager_)
     return false;
   if (window_->GetTitle() == title)
     return false;
@@ -425,7 +429,8 @@ bool NativeWidgetAura::SetWindowTitle(const base::string16& title) {
 
 void NativeWidgetAura::SetWindowIcons(const gfx::ImageSkia& window_icon,
                                       const gfx::ImageSkia& app_icon) {
-  AssignIconToAuraWindow(window_, window_icon, app_icon);
+  if (!is_parallel_widget_in_window_manager_)
+    AssignIconToAuraWindow(window_, window_icon, app_icon);
 }
 
 void NativeWidgetAura::InitModalType(ui::ModalType modal_type) {
@@ -605,7 +610,7 @@ bool NativeWidgetAura::IsActive() const {
 }
 
 void NativeWidgetAura::SetAlwaysOnTop(bool on_top) {
-  if (window_)
+  if (window_ && !is_parallel_widget_in_window_manager_)
     window_->SetProperty(aura::client::kAlwaysOnTopKey, on_top);
 }
 
@@ -808,6 +813,9 @@ ui::GestureRecognizer* NativeWidgetAura::GetGestureRecognizer() {
 }
 
 void NativeWidgetAura::OnSizeConstraintsChanged() {
+  if (is_parallel_widget_in_window_manager_)
+    return;
+
   int32_t behavior = ws::mojom::kResizeBehaviorNone;
   if (GetWidget()->widget_delegate())
     behavior = GetWidget()->widget_delegate()->GetResizeBehavior();
@@ -1115,8 +1123,15 @@ namespace internal {
 
 // static
 NativeWidgetPrivate* NativeWidgetPrivate::CreateNativeWidget(
+    const Widget::InitParams& init_params,
     internal::NativeWidgetDelegate* delegate) {
-  return new NativeWidgetAura(delegate);
+  aura::Env* env = nullptr;
+  if (init_params.parent)
+    env = init_params.parent->env();
+  else if (init_params.context)
+    env = init_params.context->env();
+  return new NativeWidgetAura(
+      delegate, /*is_parallel_widget_in_window_manager*/ false, env);
 }
 
 // static

ui/views/widget/native_widget_aura.h

@@ -21,6 +21,7 @@
 #include "ui/wm/public/activation_delegate.h"
 
 namespace aura {
+class Env;
 class Window;
 }
 
@@ -39,7 +40,12 @@ class VIEWS_EXPORT NativeWidgetAura : public internal::NativeWidgetPrivate,
                                       public aura::client::FocusChangeObserver,
                                       public aura::client::DragDropDelegate {
  public:
-  explicit NativeWidgetAura(internal::NativeWidgetDelegate* delegate);
+  // |is_parallel_widget_in_window_manager| is true only when this
+  // NativeWidgetAura is created in the window manager to represent a client
+  // window, in all other cases it's false.
+  explicit NativeWidgetAura(internal::NativeWidgetDelegate* delegate,
+                            bool is_parallel_widget_in_window_manager = false,
+                            aura::Env* env = nullptr);
 
   // Called internally by NativeWidgetAura and DesktopNativeWidgetAura to
   // associate |native_widget| with |window|.
@@ -211,6 +217,10 @@ class VIEWS_EXPORT NativeWidgetAura : public internal::NativeWidgetPrivate,
 
   internal::NativeWidgetDelegate* delegate_;
 
+  // True if the Widget is created in the window-manager and another client is
+  // embedded in it. When true certain operations are not performed.
+  const bool is_parallel_widget_in_window_manager_;
+
   // WARNING: set to NULL when destroyed. As the Widget is not necessarily
   // destroyed along with |window_| all usage of |window_| should first verify
   // non-NULL.

ui/views/widget/native_widget_mac.mm

@@ -764,6 +764,7 @@ namespace internal {
 
 // static
 NativeWidgetPrivate* NativeWidgetPrivate::CreateNativeWidget(
+    const Widget::InitParams& init_params,
     internal::NativeWidgetDelegate* delegate) {
   return new NativeWidgetMac(delegate);
 }

ui/views/widget/native_widget_private.h

@@ -51,6 +51,7 @@ class VIEWS_EXPORT NativeWidgetPrivate : public NativeWidget {
   // Creates an appropriate default NativeWidgetPrivate implementation for the
   // current OS/circumstance.
   static NativeWidgetPrivate* CreateNativeWidget(
+      const Widget::InitParams& init_params,
       internal::NativeWidgetDelegate* delegate);
 
   static NativeWidgetPrivate* GetNativeWidgetForNativeView(

ui/views/widget/widget.cc

@@ -76,7 +76,7 @@ NativeWidget* CreateNativeWidget(const Widget::InitParams& params,
     if (native_widget)
       return native_widget;
   }
-  return internal::NativeWidgetPrivate::CreateNativeWidget(delegate);
+  return internal::NativeWidgetPrivate::CreateNativeWidget(params, delegate);
 }
 
 void NotifyCaretBoundsChanged(ui::InputMethod* input_method) {