Overview: Normal drag mode only if VirtualDesks or SplitView are enabled

If neither feature is enabled, only DragToClose mode should be available

BUG=969815
TEST=Manually, Added tests

Change-Id: Iafaab2ef36a5c1f14bfcec266c3c558145a5f7f7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1642147Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Ahmed Fakhry <afakhry@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665693}

ash/BUILD.gn

@@ -1839,6 +1839,7 @@ test("ash_unittests") {
     "wm/overview/overview_controller_unittest.cc",
     "wm/overview/overview_grid_unittest.cc",
     "wm/overview/overview_session_unittest.cc",
+    "wm/overview/overview_window_drag_controller_unittest.cc",
     "wm/overview/scoped_overview_transform_window_unittest.cc",
     "wm/pip/pip_positioner_unittest.cc",
     "wm/pip/pip_test_utils.cc",

ash/wm/overview/overview_window_drag_controller.cc

@@ -132,7 +132,7 @@ void OverviewWindowDragController::Drag(const gfx::PointF& location_in_screen) {
       overview_session_->GetGridWithRootWindow(item_->root_window())
           ->StartNudge(item_);
       did_move_ = true;
-    } else {
+    } else if (should_allow_split_view_ || virtual_desks_enabled_) {
       StartNormalDragMode(location_in_screen);
     }
   }
@@ -183,6 +183,8 @@ OverviewWindowDragController::CompleteDrag(
 
 void OverviewWindowDragController::StartNormalDragMode(
     const gfx::PointF& location_in_screen) {
+  DCHECK(should_allow_split_view_ || virtual_desks_enabled_);
+
   did_move_ = true;
   current_drag_behavior_ = DragBehavior::kNormalDrag;
   Shell::Get()->mouse_cursor_filter()->ShowSharedEdgeIndicator(

ash/wm/overview/overview_window_drag_controller_unittest.cc

+// Copyright 2019 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 "ash/wm/overview/overview_window_drag_controller.h"
+
+#include "ash/public/cpp/ash_features.h"
+#include "ash/shell.h"
+#include "ash/test/ash_test_base.h"
+#include "ash/wm/mru_window_tracker.h"
+#include "ash/wm/overview/overview_controller.h"
+#include "ash/wm/overview/overview_grid.h"
+#include "ash/wm/overview/overview_item.h"
+#include "ash/wm/overview/overview_session.h"
+#include "ash/wm/window_util.h"
+#include "base/stl_util.h"
+#include "base/test/scoped_feature_list.h"
+#include "ui/events/test/event_generator.h"
+
+namespace ash {
+
+namespace {
+
+// Drags the item by |x| and |y| and does not drop it.
+void StartDraggingItemBy(OverviewItem* item,
+                         int x,
+                         int y,
+                         ui::test::EventGenerator* event_generator) {
+  const gfx::Point item_center =
+      gfx::ToRoundedPoint(item->target_bounds().CenterPoint());
+  event_generator->MoveMouseTo(item_center);
+  event_generator->PressLeftButton();
+  event_generator->MoveMouseBy(x, y);
+}
+
+// Waits for a window to be destroyed.
+class WindowCloseWaiter : public aura::WindowObserver {
+ public:
+  WindowCloseWaiter(aura::Window* window) : window_(window) {
+    DCHECK(window_);
+    window_->AddObserver(this);
+  }
+
+  ~WindowCloseWaiter() override {
+    if (window_)
+      window_->RemoveObserver(this);
+  }
+
+  void Wait() {
+    // Did window close already?
+    if (!window_)
+      return;
+
+    run_loop_.Run();
+  }
+
+  // aura::WindowObserver:
+  void OnWindowDestroyed(aura::Window* window) override {
+    window_ = nullptr;
+    run_loop_.Quit();
+  }
+
+ private:
+  aura::Window* window_;
+  base::RunLoop run_loop_;
+
+  DISALLOW_COPY_AND_ASSIGN(WindowCloseWaiter);
+};
+
+}  // namespace
+
+// Tests the behavior of window dragging in overview when both VirtualDesks and
+// Clamshell SplitView features are both disabled.
+class NoDesksNoSplitViewTest : public AshTestBase {
+ public:
+  NoDesksNoSplitViewTest() = default;
+  ~NoDesksNoSplitViewTest() override = default;
+
+  // AshTestBase:
+  void SetUp() override {
+    scoped_feature_list_.InitWithFeatures(
+        /*enabled_features=*/{},
+        /*disabled_features=*/{features::kVirtualDesks,
+                               features::kDragToSnapInClamshellMode});
+
+    AshTestBase::SetUp();
+  }
+
+ private:
+  base::test::ScopedFeatureList scoped_feature_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(NoDesksNoSplitViewTest);
+};
+
+TEST_F(NoDesksNoSplitViewTest, NormalDragIsNotPossible) {
+  auto window = CreateTestWindow(gfx::Rect(0, 0, 250, 100));
+  wm::ActivateWindow(window.get());
+  EXPECT_EQ(window.get(), wm::GetActiveWindow());
+  auto* overview_controller = Shell::Get()->overview_controller();
+  overview_controller->ToggleOverview();
+  EXPECT_TRUE(overview_controller->InOverviewSession());
+  auto* overview_session = overview_controller->overview_session();
+  auto* overview_item =
+      overview_session->GetOverviewItemForWindow(window.get());
+  ASSERT_TRUE(overview_item);
+
+  auto* event_generator = GetEventGenerator();
+  // Drag the item by an enough amount in X that would normally trigger the
+  // normal drag mode.
+  StartDraggingItemBy(overview_item, 50, 0, event_generator);
+  OverviewWindowDragController* drag_controller =
+      overview_session->window_drag_controller();
+  EXPECT_EQ(OverviewWindowDragController::DragBehavior::kUndefined,
+            drag_controller->current_drag_behavior());
+
+  // Drop the window, and expect that overview mode exits and the window is
+  // activated.
+  event_generator->ReleaseLeftButton();
+  EXPECT_FALSE(overview_controller->InOverviewSession());
+  EXPECT_EQ(window.get(), wm::GetActiveWindow());
+}
+
+TEST_F(NoDesksNoSplitViewTest, CanDoDragToClose) {
+  auto window = CreateTestWindow(gfx::Rect(0, 0, 250, 100));
+  wm::ActivateWindow(window.get());
+  EXPECT_EQ(window.get(), wm::GetActiveWindow());
+  auto* overview_controller = Shell::Get()->overview_controller();
+  overview_controller->ToggleOverview();
+  EXPECT_TRUE(overview_controller->InOverviewSession());
+  auto* overview_session = overview_controller->overview_session();
+  auto* overview_item =
+      overview_session->GetOverviewItemForWindow(window.get());
+  ASSERT_TRUE(overview_item);
+
+  auto* event_generator = GetEventGenerator();
+  // Dragging with a bigger Y-component than X should trigger the drag-to-close
+  // mode.
+  StartDraggingItemBy(overview_item, 30, 50, event_generator);
+  OverviewWindowDragController* drag_controller =
+      overview_session->window_drag_controller();
+  EXPECT_EQ(OverviewWindowDragController::DragBehavior::kDragToClose,
+            drag_controller->current_drag_behavior());
+
+  // Continue dragging vertically and drop. Expect that overview exists since
+  // it's the only window on the grid.
+  event_generator->MoveMouseBy(0, 200);
+  // release() the window as it will be closed and destroyed when we drop it.
+  aura::Window* window_ptr = window.release();
+  WindowCloseWaiter waiter{window_ptr};
+  event_generator->ReleaseLeftButton();
+  waiter.Wait();
+  EXPECT_FALSE(overview_controller->InOverviewSession());
+  EXPECT_FALSE(base::ContainsValue(
+      Shell::Get()->mru_window_tracker()->BuildMruWindowList(kAllDesks),
+      window_ptr));
+}
+
+}  // namespace ash