[platform] Call OnNativeWidgetDestroying on CloseNow call.

Ensure that a native widget gets a destroying call to ensure a right
destruction order and SiteProcessCountTracker can eventually
decrement process count.

Otherwise, a DCHECK in dtor of SiteProcessCountTracker is called.

TEST: ./out/OzoneLinux/views_unittests --ozone-platform=wayland
--gtest_filter=DesktopWindowTreeHostPlatformTest.CallOnNativeWidgetDestroying

Change-Id: I82f39a8e9673b9737215cf85e7810dbb0af78ceb
Reviewed-on: https://chromium-review.googlesource.com/1154530
Commit-Queue: Maksim Sisov <msisov@igalia.com>
Reviewed-by: Sadrul Chowdhury <sadrul@chromium.org>
Cr-Commit-Position: refs/heads/master@{#579782}

ui/views/BUILD.gn

@@ -1151,6 +1151,11 @@ test("views_unittests") {
     }
   }
 
+  if (is_linux && !is_chromeos && !use_x11) {
+    sources +=
+        [ "widget/desktop_aura/desktop_window_tree_host_platform_unittest.cc" ]
+  }
+
   if (!is_chromeos) {
     sources += [ "widget/desktop_widget_unittest.cc" ]
   }

ui/views/widget/desktop_aura/desktop_window_tree_host_platform.cc

@@ -135,6 +135,8 @@ void DesktopWindowTreeHostPlatform::CloseNow() {
   if (!weak_ref || got_on_closed_)
     return;
 
+  native_widget_delegate_->OnNativeWidgetDestroying();
+
   got_on_closed_ = true;
   desktop_native_widget_aura_->OnHostClosed();
 }

ui/views/widget/desktop_aura/desktop_window_tree_host_platform_unittest.cc

+// Copyright 2018 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/desktop_aura/desktop_window_tree_host_platform.h"
+#include "base/run_loop.h"
+#include "ui/views/test/views_test_base.h"
+#include "ui/views/widget/desktop_aura/desktop_native_widget_aura.h"
+#include "ui/views/widget/widget_observer.h"
+
+namespace views {
+
+namespace {
+
+class WidgetDestroyingObserver : public WidgetObserver {
+ public:
+  explicit WidgetDestroyingObserver(Widget* widget) : widget_(widget) {
+    widget_->AddObserver(this);
+  }
+  ~WidgetDestroyingObserver() override {
+    if (widget_)
+      widget_->RemoveObserver(this);
+  }
+
+  // Returns immediately when |widget_| becomes NULL, otherwise a RunLoop is
+  // used until widget closing event is received.
+  void Wait() {
+    if (!on_widget_destroying_)
+      run_loop_.Run();
+  }
+
+  bool widget_destroying() const { return on_widget_destroying_; }
+
+ private:
+  // views::WidgetObserver override:
+  void OnWidgetDestroying(Widget* widget) override {
+    DCHECK_EQ(widget_, widget);
+    widget_->RemoveObserver(this);
+    widget_ = nullptr;
+    on_widget_destroying_ = true;
+    if (run_loop_.running())
+      run_loop_.Quit();
+  }
+
+  Widget* widget_;
+  base::RunLoop run_loop_;
+  bool on_widget_destroying_ = false;
+
+  DISALLOW_COPY_AND_ASSIGN(WidgetDestroyingObserver);
+};
+
+std::unique_ptr<Widget> CreateWidgetWithNativeWidget() {
+  std::unique_ptr<Widget> widget(new Widget);
+  Widget::InitParams params(Widget::InitParams::TYPE_WINDOW);
+  params.delegate = nullptr;
+  params.ownership = Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
+  params.remove_standard_frame = true;
+  params.native_widget = new DesktopNativeWidgetAura(widget.get());
+  params.bounds = gfx::Rect(100, 100, 100, 100);
+  widget->Init(params);
+  return widget;
+}
+
+}  // namespace
+
+class DesktopWindowTreeHostPlatformTest : public ViewsTestBase {
+ public:
+  DesktopWindowTreeHostPlatformTest() {}
+  ~DesktopWindowTreeHostPlatformTest() override {}
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DesktopWindowTreeHostPlatformTest);
+};
+
+TEST_F(DesktopWindowTreeHostPlatformTest, CallOnNativeWidgetDestroying) {
+  std::unique_ptr<Widget> widget = CreateWidgetWithNativeWidget();
+
+  WidgetDestroyingObserver observer(
+      widget->native_widget_private()->GetWidget());
+  widget->CloseNow();
+
+  observer.Wait();
+  EXPECT_TRUE(observer.widget_destroying());
+}
+
+}  // namespace views