Reland "Ash Tray: Refactor slide out animation to re-use transform animation."

This is a reland of fc7ae248

Original change's description:
> Ash Tray: Refactor slide out animation to re-use transform animation.
> 
> There are currently two code paths to slide out a notification in the message
> center, which this CL rationalize this logic to just use the transform-based
> animation.
> 
> Furthermore, to implement the spec'd clear all animation, each MessageView
> needs to be animated separately, which isn't currently possible.
> 
> Note: the clear all animation still uses the old Layout() based slide-out
> animation. This will be removed once the spec'd clear all is implemented.
> 
> TEST=verified existing behaviour with normal and ARC++ notifications,
>      updated unit test
> BUG=897915
> 
> Change-Id: I294f4fe326730cf40a447c23d551e7d33838a579
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1613919
> Commit-Queue: Tim Song <tengs@chromium.org>
> Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#661553}

Bug: 897915
Change-Id: Ice73af1f3982d74f6b9c3006235165c52a0f4c7d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1621539Reviewed-by: Tetsui Ohkubo <tetsui@chromium.org>
Commit-Queue: Tim Song <tengs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#662266}

ash/system/message_center/unified_message_center_view_unittest.cc

@@ -15,6 +15,7 @@
 #include "ash/system/unified/unified_system_tray_model.h"
 #include "ash/test/ash_test_base.h"
 #include "base/macros.h"
+#include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/scoped_feature_list.h"
@@ -80,6 +81,7 @@ class UnifiedMessageCenterViewTest : public AshTestBase,
   }
 
   void TearDown() override {
+    base::RunLoop().RunUntilIdle();
     message_center_view_.reset();
     model_.reset();
     AshTestBase::TearDown();
@@ -126,13 +128,19 @@ class UnifiedMessageCenterViewTest : public AshTestBase,
 
   void AnimateMessageListToMiddle() { AnimateMessageListToValue(0.5); }
 
-  void AnimateMessageListToEnd() { GetMessageListView()->animation_->End(); }
+  void AnimateMessageListToEnd() {
+    FinishMessageListSlideOutAnimations();
+    GetMessageListView()->animation_->End();
+  }
 
   void AnimateMessageListUntilIdle() {
-    while (GetMessageListView()->animation_->is_animating())
+    while (GetMessageListView()->animation_->is_animating()) {
       GetMessageListView()->animation_->End();
+    }
   }
 
+  void FinishMessageListSlideOutAnimations() { base::RunLoop().RunUntilIdle(); }
+
   gfx::Rect GetMessageViewVisibleBounds(size_t index) {
     gfx::Rect bounds = GetMessageListView()->children()[index]->bounds();
     bounds -= GetScroller()->GetVisibleRect().OffsetFromOrigin();
@@ -236,7 +244,7 @@ TEST_F(UnifiedMessageCenterViewTest, AddAndRemoveNotification) {
   auto* collapse_animation = GetMessageCenterAnimation();
   collapse_animation->SetCurrentValue(0.5);
   message_center_view()->AnimationProgressed(collapse_animation);
-  AnimateMessageListToMiddle();
+  AnimateMessageListToEnd();
   EXPECT_TRUE(message_center_view()->GetVisible());
 
   // The message center is now hidden after all animations complete.
@@ -263,12 +271,7 @@ TEST_F(UnifiedMessageCenterViewTest, RemoveNotificationAtTail) {
   // Remove the last notification.
   MessageCenter::Get()->RemoveNotification(id_to_remove, true /* by_user */);
 
-  // The first animation slides the notification out of the list, and the second
-  // animation collapses the list.
-  AnimateMessageListToEnd();
-  AnimateMessageListToValue(0);
-
-  // The scroll position should not change after sliding the notification out
+  // The scroll position should not change before sliding the notification out
   // and instead should wait until the animation finishes.
   EXPECT_EQ(scroll_position, GetScroller()->GetVisibleRect().y());
 
@@ -297,7 +300,7 @@ TEST_F(UnifiedMessageCenterViewTest, ContentsRelayout) {
   const int previous_list_height = GetMessageListView()->height();
 
   MessageCenter::Get()->RemoveNotification(ids.back(), true /* by_user */);
-  AnimateMessageListUntilIdle();
+  AnimateMessageListToEnd();
   EXPECT_TRUE(message_center_view()->GetVisible());
   EXPECT_GT(previous_contents_height, GetScrollerContents()->height());
   EXPECT_GT(previous_list_height, GetMessageListView()->height());
@@ -535,7 +538,7 @@ TEST_F(UnifiedMessageCenterViewTest, StackingCounterRemovedWithNotifications) {
   EXPECT_TRUE(GetStackingCounter()->GetVisible());
   for (size_t i = 0; i < 5; ++i) {
     MessageCenter::Get()->RemoveNotification(ids[i], true /* by_user */);
-    AnimateMessageListUntilIdle();
+    AnimateMessageListToEnd();
   }
   EXPECT_FALSE(GetStackingCounter()->GetVisible());
 }
@@ -629,7 +632,7 @@ TEST_F(UnifiedMessageCenterViewTest,
   EXPECT_TRUE(GetStackingCounter()->GetVisible());
   for (size_t i = 0; i < 4; ++i) {
     MessageCenter::Get()->RemoveNotification(ids[i], true /* by_user */);
-    AnimateMessageListUntilIdle();
+    AnimateMessageListToEnd();
   }
   EXPECT_TRUE(GetStackingCounter()->GetVisible());
   EXPECT_FALSE(GetStackingCounterLabel()->GetVisible());
@@ -808,7 +811,7 @@ TEST_F(UnifiedMessageCenterViewTest, FocusClearedAfterNotificationRemoval) {
 
   // Remove the notification and observe that the focus is cleared.
   MessageCenter::Get()->RemoveNotification(id1, true /* by_user */);
-  AnimateMessageListUntilIdle();
+  AnimateMessageListToEnd();
   EXPECT_FALSE(message_center_view()->GetFocusManager()->GetFocusedView());
 
   widget->GetRootView()->RemoveChildView(message_center_view());

ash/system/message_center/unified_message_list_view.cc

@@ -29,7 +29,7 @@ namespace ash {
 namespace {
 
 constexpr base::TimeDelta kClosingAnimationDuration =
-    base::TimeDelta::FromMilliseconds(330);
+    base::TimeDelta::FromMilliseconds(320);
 constexpr base::TimeDelta kClearAllStackedAnimationDuration =
     base::TimeDelta::FromMilliseconds(40);
 constexpr base::TimeDelta kClearAllVisibleAnimationDuration =
@@ -69,8 +69,10 @@ class UnifiedMessageListView::MessageViewContainer
     : public views::View,
       public MessageView::SlideObserver {
  public:
-  explicit MessageViewContainer(MessageView* message_view)
+  MessageViewContainer(MessageView* message_view,
+                       UnifiedMessageListView* list_view)
       : message_view_(message_view),
+        list_view_(list_view),
         control_view_(new NotificationSwipeControlView(message_view)) {
     message_view_->AddSlideObserver(this);
 
@@ -79,7 +81,7 @@ class UnifiedMessageListView::MessageViewContainer
     AddChildView(message_view_);
   }
 
-  ~MessageViewContainer() override = default;
+  ~MessageViewContainer() override { message_view_->RemoveSlideObserver(this); }
 
   // Update the border and background corners based on if the notification is
   // at the top or the bottom.
@@ -125,6 +127,10 @@ class UnifiedMessageListView::MessageViewContainer
     }
   }
 
+  void SlideOutAndClose() {
+    message_view_->SlideOutAndClose(1 /* direction */);
+  }
+
   std::string GetNotificationId() const {
     return message_view_->notification_id();
   }
@@ -160,7 +166,9 @@ class UnifiedMessageListView::MessageViewContainer
   }
 
   void OnSlideOut(const std::string& notification_id) override {
-    is_slid_out_by_user_ = true;
+    is_slid_out_ = true;
+    set_is_removed();
+    list_view_->OnNotificationSlidOut();
   }
 
   gfx::Rect start_bounds() const { return start_bounds_; }
@@ -177,7 +185,7 @@ class UnifiedMessageListView::MessageViewContainer
 
   void set_is_removed() { is_removed_ = true; }
 
-  bool is_slid_out_by_user() { return is_slid_out_by_user_; }
+  bool is_slid_out() { return is_slid_out_; }
 
  private:
   // The bounds that the container starts animating from. If not animating, it's
@@ -188,14 +196,14 @@ class UnifiedMessageListView::MessageViewContainer
   // actual bounds().
   gfx::Rect ideal_bounds_;
 
-  // True when the notification is removed and during SLIDE_OUT animation.
-  // Unused if |state_| is not SLIDE_OUT.
+  // True when the notification is removed and during slide out animation.
   bool is_removed_ = false;
 
-  // True if the notification is slid out completely by the user.
-  bool is_slid_out_by_user_ = false;
+  // True if the notification is slid out completely.
+  bool is_slid_out_ = false;
 
   MessageView* const message_view_;
+  UnifiedMessageListView* const list_view_;
   NotificationSwipeControlView* const control_view_;
 
   DISALLOW_COPY_AND_ASSIGN(MessageViewContainer);
@@ -224,7 +232,8 @@ UnifiedMessageListView::~UnifiedMessageListView() {
 void UnifiedMessageListView::Init() {
   bool is_latest = true;
   for (auto* notification : MessageCenter::Get()->GetVisibleNotifications()) {
-    auto* view = new MessageViewContainer(CreateMessageView(*notification));
+    auto* view =
+        new MessageViewContainer(CreateMessageView(*notification), this);
     view->LoadExpandedState(model_, is_latest);
     AddChildViewAt(view, 0);
     MessageCenter::Get()->DisplayedNotification(
@@ -333,7 +342,7 @@ void UnifiedMessageListView::OnNotificationAdded(const std::string& id) {
   auto* view = CreateMessageView(*notification);
   // Expand the latest notification.
   view->SetExpanded(view->IsAutoExpandingAllowed());
-  AddChildView(new MessageViewContainer(view));
+  AddChildView(new MessageViewContainer(view, this));
   UpdateBorders();
   ResetBounds();
 }
@@ -342,18 +351,32 @@ void UnifiedMessageListView::OnNotificationRemoved(const std::string& id,
                                                    bool by_user) {
   if (ignore_notification_remove_)
     return;
+
+  // The corresponding MessageView may have already been deleted after being
+  // manually slid out.
+  auto* child = GetNotificationById(id);
+  if (!child)
+    return;
+
   InterruptClearAll();
   ResetBounds();
 
-  auto* child = GetNotificationById(id);
-  if (child)
-    child->set_is_removed();
+  child->set_is_removed();
 
-  state_ = child->is_slid_out_by_user() ? State::MOVE_DOWN : State::SLIDE_OUT;
+  // If the MessageView is slid out, then do nothing here. The MOVE_DOWN
+  // animation will be started in OnNotificationSlidOut().
+  if (!child->is_slid_out())
+    child->SlideOutAndClose();
+}
 
-  if (child->is_slid_out_by_user())
-    DeleteRemovedNotifications();
+void UnifiedMessageListView::OnNotificationSlidOut() {
+  DeleteRemovedNotifications();
 
+  // |message_center_view_| can be null in tests.
+  if (message_center_view_)
+    message_center_view_->OnNotificationSlidOut();
+
+  state_ = State::MOVE_DOWN;
   UpdateBounds();
   StartAnimation();
 }
@@ -365,10 +388,13 @@ void UnifiedMessageListView::OnNotificationUpdated(const std::string& id) {
 
   InterruptClearAll();
 
+  // The corresponding MessageView may have been slid out and deleted, so just
+  // ignore this update as the notification will soon be deleted.
   auto* child = GetNotificationById(id);
-  if (child)
-    child->UpdateWithNotification(*notification);
+  if (!child)
+    return;
 
+  child->UpdateWithNotification(*notification);
   ResetBounds();
 }
 
@@ -388,12 +414,7 @@ void UnifiedMessageListView::AnimationEnded(const gfx::Animation* animation) {
   animation_->SetCurrentValue(1.0);
   PreferredSizeChanged();
 
-  if (state_ == State::SLIDE_OUT) {
-    DeleteRemovedNotifications();
-    UpdateBounds();
-
-    state_ = State::MOVE_DOWN;
-  } else if (state_ == State::MOVE_DOWN) {
+  if (state_ == State::MOVE_DOWN) {
     state_ = State::IDLE;
   } else if (state_ == State::CLEAR_ALL_STACKED ||
              state_ == State::CLEAR_ALL_VISIBLE) {
@@ -541,14 +562,7 @@ void UnifiedMessageListView::StartAnimation() {
   switch (state_) {
     case State::IDLE:
       break;
-    case State::SLIDE_OUT:
-      animation_->SetDuration(kClosingAnimationDuration);
-      animation_->Start();
-      break;
     case State::MOVE_DOWN:
-      // |message_center_view_| can be null in tests.
-      if (message_center_view_)
-        message_center_view_->OnNotificationSlidOut();
       animation_->SetDuration(kClosingAnimationDuration);
       animation_->Start();
       break;
@@ -600,11 +614,10 @@ void UnifiedMessageListView::UpdateClearAllAnimation() {
 }
 
 double UnifiedMessageListView::GetCurrentValue() const {
-  return gfx::Tween::CalculateValue(
-      state_ == State::SLIDE_OUT || state_ == State::CLEAR_ALL_VISIBLE
-          ? gfx::Tween::EASE_IN
-          : gfx::Tween::FAST_OUT_SLOW_IN,
-      animation_->GetCurrentValue());
+  return gfx::Tween::CalculateValue(state_ == State::CLEAR_ALL_VISIBLE
+                                        ? gfx::Tween::EASE_IN
+                                        : gfx::Tween::FAST_OUT_SLOW_IN,
+                                    animation_->GetCurrentValue());
 }
 
 }  // namespace ash

ash/system/message_center/unified_message_list_view.h

@@ -68,6 +68,10 @@ class ASH_EXPORT UnifiedMessageListView
   // Returns true if an animation is currently in progress.
   bool IsAnimating() const;
 
+  // Called when a notification is slid out so we can run the MOVE_DOWN
+  // animation.
+  void OnNotificationSlidOut();
+
   // views::View:
   void ChildPreferredSizeChanged(views::View* child) override;
   void PreferredSizeChanged() override;
@@ -113,9 +117,6 @@ class ASH_EXPORT UnifiedMessageListView
     // No animation is running.
     IDLE,
 
-    // Sliding out a removed notification. It will transition to MOVE_DOWN.
-    SLIDE_OUT,
-
     // Moving down notifications.
     MOVE_DOWN,
 

ash/system/message_center/unified_message_list_view_unittest.cc

@@ -8,9 +8,11 @@
 #include "ash/system/tray/tray_constants.h"
 #include "ash/system/unified/unified_system_tray_model.h"
 #include "ash/test/ash_test_base.h"
+#include "base/run_loop.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/test/scoped_feature_list.h"
+#include "ui/compositor/layer_animator.h"
 #include "ui/message_center/message_center.h"
 #include "ui/message_center/views/message_view.h"
 #include "ui/message_center/views/notification_view_md.h"
@@ -26,7 +28,11 @@ namespace {
 class TestNotificationView : public message_center::NotificationViewMD {
  public:
   TestNotificationView(const message_center::Notification& notification)
-      : NotificationViewMD(notification) {}
+      : NotificationViewMD(notification) {
+    layer()->GetAnimator()->set_preemption_strategy(
+        ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
+  }
+
   ~TestNotificationView() override = default;
 
   // message_center::NotificationViewMD:
@@ -139,6 +145,8 @@ class UnifiedMessageListViewTest : public AshTestBase,
     return message_list_view()->children()[index]->bounds();
   }
 
+  void FinishSlideOutAnimation() { base::RunLoop().RunUntilIdle(); }
+
   void AnimateToMiddle() {
     EXPECT_TRUE(IsAnimating());
     message_list_view()->animation_->SetCurrentValue(0.5);
@@ -164,6 +172,10 @@ class UnifiedMessageListViewTest : public AshTestBase,
 
   int size_changed_count() const { return size_changed_count_; }
 
+  ui::LayerAnimator* LayerAnimatorAt(int i) {
+    return GetMessageViewAt(i)->layer()->GetAnimator();
+  }
+
  private:
   base::test::ScopedFeatureList scoped_feature_list_;
   int id_ = 0;
@@ -246,13 +258,15 @@ TEST_F(UnifiedMessageListViewTest, RemoveNotification) {
   CreateMessageListView();
   int previous_height = message_list_view()->GetPreferredSize().height();
 
+  EXPECT_EQ(2u, message_list_view()->children().size());
   EXPECT_EQ(kUnifiedTrayCornerRadius, GetMessageViewAt(0)->top_radius());
   EXPECT_EQ(0, GetMessageViewAt(0)->bottom_radius());
 
   gfx::Rect previous_bounds = GetMessageViewBounds(0);
   MessageCenter::Get()->RemoveNotification(id0, true /* by_user */);
+  FinishSlideOutAnimation();
   AnimateUntilIdle();
-  EXPECT_EQ(3, size_changed_count());
+  EXPECT_EQ(1u, message_list_view()->children().size());
   EXPECT_EQ(previous_bounds.y(), GetMessageViewBounds(0).y());
   EXPECT_LT(0, message_list_view()->GetPreferredSize().height());
   EXPECT_GT(previous_height, message_list_view()->GetPreferredSize().height());
@@ -261,8 +275,9 @@ TEST_F(UnifiedMessageListViewTest, RemoveNotification) {
   EXPECT_EQ(kUnifiedTrayCornerRadius, GetMessageViewAt(0)->bottom_radius());
 
   MessageCenter::Get()->RemoveNotification(id1, true /* by_user */);
+  FinishSlideOutAnimation();
   AnimateUntilIdle();
-  EXPECT_EQ(6, size_changed_count());
+  EXPECT_EQ(0u, message_list_view()->children().size());
   EXPECT_EQ(0, message_list_view()->GetPreferredSize().height());
 }
 
@@ -300,11 +315,7 @@ TEST_F(UnifiedMessageListViewTest, RemovingNotificationAnimation) {
   gfx::Rect bounds1 = GetMessageViewBounds(1);
 
   MessageCenter::Get()->RemoveNotification(id1, true /* by_user */);
-  AnimateToMiddle();
-  gfx::Rect slided_bounds = GetMessageViewBounds(1);
-  EXPECT_LT(bounds1.x(), slided_bounds.x());
-  AnimateToEnd();
-
+  FinishSlideOutAnimation();
   AnimateToMiddle();
   EXPECT_GT(previous_height, message_list_view()->GetPreferredSize().height());
   previous_height = message_list_view()->GetPreferredSize().height();
@@ -315,7 +326,7 @@ TEST_F(UnifiedMessageListViewTest, RemovingNotificationAnimation) {
   EXPECT_EQ(bounds1, GetMessageViewBounds(1));
 
   MessageCenter::Get()->RemoveNotification(id2, true /* by_user */);
-  AnimateToEnd();
+  FinishSlideOutAnimation();
   AnimateToMiddle();
   EXPECT_GT(previous_height, message_list_view()->GetPreferredSize().height());
   previous_height = message_list_view()->GetPreferredSize().height();
@@ -325,7 +336,7 @@ TEST_F(UnifiedMessageListViewTest, RemovingNotificationAnimation) {
   EXPECT_EQ(bounds0, GetMessageViewBounds(0));
 
   MessageCenter::Get()->RemoveNotification(id0, true /* by_user */);
-  AnimateToEnd();
+  FinishSlideOutAnimation();
   AnimateToMiddle();
   EXPECT_GT(previous_height, message_list_view()->GetPreferredSize().height());
   previous_height = message_list_view()->GetPreferredSize().height();
@@ -340,6 +351,7 @@ TEST_F(UnifiedMessageListViewTest, ResetAnimation) {
   CreateMessageListView();
 
   MessageCenter::Get()->RemoveNotification(id0, true /* by_user */);
+  FinishSlideOutAnimation();
   EXPECT_TRUE(IsAnimating());
   AnimateToMiddle();
 
@@ -520,7 +532,7 @@ TEST_F(UnifiedMessageListViewTest, ClearAllWithPinnedNotifications) {
 TEST_F(UnifiedMessageListViewTest, UserSwipesAwayNotification) {
   // Show message list with two notifications.
   AddNotification();
-  AddNotification();
+  auto id1 = AddNotification();
   CreateMessageListView();
 
   // Start swiping the notification away.
@@ -531,7 +543,8 @@ TEST_F(UnifiedMessageListViewTest, UserSwipesAwayNotification) {
 
   // Swiping away the notification should remove it both in the MessageCenter
   // and the MessageListView.
-  GetMessageViewAt(1)->OnSlideOut();
+  MessageCenter::Get()->RemoveNotification(id1, true /* by_user */);
+  FinishSlideOutAnimation();
   EXPECT_EQ(1u, MessageCenter::Get()->GetVisibleNotifications().size());
   EXPECT_EQ(1u, message_list_view()->children().size());
 

ui/message_center/views/message_view.cc

@@ -130,6 +130,10 @@ void MessageView::CloseSwipeControl() {
   slide_out_controller_.CloseSwipeControl();
 }
 
+void MessageView::SlideOutAndClose(int direction) {
+  slide_out_controller_.SlideOutAndClose(direction);
+}
+
 void MessageView::SetExpanded(bool expanded) {
   // Not implemented by default.
 }
@@ -304,27 +308,31 @@ ui::Layer* MessageView::GetSlideOutLayer() {
 }
 
 void MessageView::OnSlideStarted() {
-  for (auto* observer : slide_observers_) {
-    observer->OnSlideStarted(notification_id_);
+  for (auto& observer : slide_observers_) {
+    observer.OnSlideStarted(notification_id_);
   }
 }
 
 void MessageView::OnSlideChanged(bool in_progress) {
-  for (auto* observer : slide_observers_) {
-    observer->OnSlideChanged(notification_id_);
+  for (auto& observer : slide_observers_) {
+    observer.OnSlideChanged(notification_id_);
   }
 }
 
 void MessageView::AddSlideObserver(MessageView::SlideObserver* observer) {
-  slide_observers_.push_back(observer);
+  slide_observers_.AddObserver(observer);
 }
 
-void MessageView::OnSlideOut() {
-  for (auto* observer : slide_observers_)
-    observer->OnSlideOut(notification_id_);
+void MessageView::RemoveSlideObserver(MessageView::SlideObserver* observer) {
+  slide_observers_.RemoveObserver(observer);
+}
 
+void MessageView::OnSlideOut() {
   MessageCenter::Get()->RemoveNotification(notification_id_,
                                            true /* by_user */);
+
+  for (auto& observer : slide_observers_)
+    observer.OnSlideOut(notification_id_);
 }
 
 void MessageView::OnWillChangeFocus(views::View* before, views::View* now) {}

ui/message_center/views/message_view.h

@@ -8,6 +8,7 @@
 #include <memory>
 
 #include "base/macros.h"
+#include "base/observer_list.h"
 #include "base/strings/string16.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkColor.h"
@@ -92,6 +93,7 @@ class MESSAGE_CENTER_EXPORT MessageView : public views::InkDropHostView,
   virtual bool IsManuallyExpandedOrCollapsed() const;
   virtual void SetManuallyExpandedOrCollapsed(bool value);
   virtual void CloseSwipeControl();
+  virtual void SlideOutAndClose(int direction);
 
   // Update corner radii of the notification. Subclasses will override this to
   // implement rounded corners if they don't use MessageView's default
@@ -136,6 +138,7 @@ class MESSAGE_CENTER_EXPORT MessageView : public views::InkDropHostView,
   void OnDidChangeFocus(views::View* before, views::View* now) override;
 
   void AddSlideObserver(SlideObserver* observer);
+  void RemoveSlideObserver(SlideObserver* observer);
 
   Mode GetMode() const;
 
@@ -190,7 +193,7 @@ class MESSAGE_CENTER_EXPORT MessageView : public views::InkDropHostView,
   std::unique_ptr<views::Painter> focus_painter_;
 
   SlideOutController slide_out_controller_;
-  std::vector<SlideObserver*> slide_observers_;
+  base::ObserverList<SlideObserver>::Unchecked slide_observers_;
 
   // True if |this| is embedded in another view. Equivalent to |!top_level| in
   // MessageViewFactory parlance.

ui/message_center/views/slide_out_controller.cc

@@ -15,6 +15,7 @@ namespace message_center {
 namespace {
 constexpr int kSwipeRestoreDurationMs = 150;
 constexpr int kSwipeOutTotalDurationMs = 150;
+gfx::Tween::Type kSwipeTweenType = gfx::Tween::EASE_IN;
 }  // anonymous namespace
 
 SlideOutController::SlideOutController(ui::EventTarget* target,
@@ -171,6 +172,7 @@ void SlideOutController::SetTransformWithAnimationIfNecessary(
   if (layer->transform() != transform) {
     ui::ScopedLayerAnimationSettings settings(layer->GetAnimator());
     settings.SetTransitionDuration(animation_duration);
+    settings.SetTweenType(kSwipeTweenType);
     settings.AddObserver(this);
 
     // An animation starts. OnImplicitAnimationsCompleted will be called just

ui/message_center/views/slide_out_controller.h

@@ -70,6 +70,10 @@ class MESSAGE_CENTER_EXPORT SlideOutController
   // Effective only when swipe control is enabled by EnableSwipeControl().
   void CloseSwipeControl();
 
+  // Slides the view out and closes it after the animation. The sign of
+  // |direction| indicates which way the slide occurs.
+  void SlideOutAndClose(int direction);
+
  private:
   // Positions where the slided view stays after the touch released.
   enum class SwipeControlOpenState { CLOSED, OPEN_ON_LEFT, OPEN_ON_RIGHT };
@@ -80,10 +84,6 @@ class MESSAGE_CENTER_EXPORT SlideOutController
   // Decides which position the slide should go back after touch is released.
   void CaptureControlOpenState();
 
-  // Slides the view out and closes it after the animation. The sign of
-  // |direction| indicates which way the slide occurs.
-  void SlideOutAndClose(int direction);
-
   // Sets the opacity of the slide out layer if |update_opacity_| is true.
   void SetOpacityIfNecessary(float opacity);