Revert "overview: Introduce OnOverviewStartAnimationComplete observer."

This reverts commit 77cbc4f0.

Reason for revert:
Suspect compile failure on linux-chromeos-dbg.

Example:
https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/linux-chromeos-dbg/8511

Log:
FAILED: ash_unittests 
../../buildtools/third_party/libc++/trunk/include/memory:5091: error: undefined reference to 'ash::StartAnimationObserver::StartAnimationObserver()'
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Original change's description:
> overview: Introduce OnOverviewStartAnimationComplete observer.
> 
> Introdue a new overview observer which notifies observers when the start
> animation for overview is different.
> 
> Uses will be both in and out of overview - for example adding mask, shadow
> and animating tray, shelf.
> 
> Also modify CleanupObserverTest to use some new stuff.
> 
> Test: ash_unittests StartAnimationObserverTest.Basic
> Bug: 898222
> Change-Id: I86bdd253f0a4a4dd81ad6ba03780baf07923d256
> Reviewed-on: https://chromium-review.googlesource.com/c/1297405
> Commit-Queue: Sammie Quon <sammiequon@chromium.org>
> Reviewed-by: Mitsuru Oshima <oshima@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#602941}

TBR=oshima@chromium.org,sammiequon@chromium.org

Change-Id: I5038dbe64ae02fb0f71a7c4ffcc36bcfaaca13ca
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 898222
Reviewed-on: https://chromium-review.googlesource.com/c/1300815Reviewed-by: Takashi Sakamoto <tasak@google.com>
Commit-Queue: Takashi Sakamoto <tasak@google.com>
Cr-Commit-Position: refs/heads/master@{#602972}

ash/BUILD.gn

@@ -1187,8 +1187,6 @@ component("ash") {
     "wm/overview/scoped_overview_animation_settings.h",
     "wm/overview/scoped_transform_overview_window.cc",
     "wm/overview/scoped_transform_overview_window.h",
-    "wm/overview/start_animation_observer.cc",
-    "wm/overview/start_animation_observer.h",
     "wm/overview/window_grid.cc",
     "wm/overview/window_grid.h",
     "wm/overview/window_selector.cc",
@@ -1933,7 +1931,6 @@ test("ash_unittests") {
     "wm/overlay_event_filter_unittest.cc",
     "wm/overlay_layout_manager_unittest.cc",
     "wm/overview/cleanup_animation_observer_unittest.cc",
-    "wm/overview/start_animation_observer_unittest.cc",
     "wm/overview/window_selector_controller_unittest.cc",
     "wm/overview/window_selector_unittest.cc",
     "wm/pip/pip_positioner_unittest.cc",

ash/app_list/app_list_controller_impl.cc

@@ -521,9 +521,8 @@ void AppListControllerImpl::OnOverviewModeEnding() {
       WindowSelector::EnterExitOverviewType::kWindowsMinimized;
 }
 
-void AppListControllerImpl::OnOverviewModeEndingAnimationComplete(
-    bool canceled) {
-  if (!IsHomeLauncherEnabledInTabletMode() || canceled)
+void AppListControllerImpl::OnOverviewModeEndingAnimationComplete() {
+  if (!IsHomeLauncherEnabledInTabletMode())
     return;
 
   presenter_.ScheduleOverviewModeAnimation(/*start=*/false,

ash/app_list/app_list_controller_impl.h

@@ -197,7 +197,7 @@ class ASH_EXPORT AppListControllerImpl
   // ShellObserver:
   void OnOverviewModeStarting() override;
   void OnOverviewModeEnding() override;
-  void OnOverviewModeEndingAnimationComplete(bool canceled) override;
+  void OnOverviewModeEndingAnimationComplete() override;
 
   // TabletModeObserver:
   void OnTabletModeStarted() override;

ash/shell.cc

@@ -585,11 +585,6 @@ void Shell::NotifyOverviewModeStarting() {
     observer.OnOverviewModeStarting();
 }
 
-void Shell::NotifyOverviewModeStartingAnimationComplete(bool canceled) {
-  for (auto& observer : shell_observers_)
-    observer.OnOverviewModeStartingAnimationComplete(canceled);
-}
-
 void Shell::NotifyOverviewModeEnding() {
   for (auto& observer : shell_observers_)
     observer.OnOverviewModeEnding();
@@ -600,9 +595,9 @@ void Shell::NotifyOverviewModeEnded() {
     observer.OnOverviewModeEnded();
 }
 
-void Shell::NotifyOverviewModeEndingAnimationComplete(bool canceled) {
+void Shell::NotifyOverviewModeEndingAnimationComplete() {
   for (auto& observer : shell_observers_)
-    observer.OnOverviewModeEndingAnimationComplete(canceled);
+    observer.OnOverviewModeEndingAnimationComplete();
 }
 
 void Shell::NotifySplitViewModeStarting() {

ash/shell.h

@@ -602,18 +602,15 @@ class ASH_EXPORT Shell : public SessionObserver,
   // windows get re-arranged).
   void NotifyOverviewModeStarting();
 
-  // Notifies observers that the start overview mode animation has completed.
-  void NotifyOverviewModeStartingAnimationComplete(bool canceled);
-
-  // Notifies observers that overview mode is about to end (before the windows
+  // Notifies observers that overview mode is about to end (bofore the windows
   // restore themselves).
   void NotifyOverviewModeEnding();
 
   // Notifies observers that overview mode has ended.
   void NotifyOverviewModeEnded();
 
-  // Notifies observers that the end overview mode animation has completed.
-  void NotifyOverviewModeEndingAnimationComplete(bool canceled);
+  // Notifies observers that the end overivew mode animation has completed.
+  void NotifyOverviewModeEndingAnimationComplete();
 
   // Notifies observers that split view mode is about to be started (before the
   // window gets snapped and activated).

ash/shell_observer.h

@@ -45,11 +45,6 @@ class ASH_EXPORT ShellObserver {
   // get re-arranged).
   virtual void OnOverviewModeStarting() {}
 
-  // Called after the animations that happen when overview mode is started are
-  // complete. If |canceled| it means overview was quit before the start
-  // animations were finished.
-  virtual void OnOverviewModeStartingAnimationComplete(bool canceled) {}
-
   // Called when the overview mode is about to end (bofore the windows restore
   // themselves).
   virtual void OnOverviewModeEnding() {}
@@ -58,9 +53,8 @@ class ASH_EXPORT ShellObserver {
   virtual void OnOverviewModeEnded() {}
 
   // Called after the animations that happen when overview mode is ended are
-  // complete. If |canceled| it means overview was reentered before the exit
-  // animations were finished.
-  virtual void OnOverviewModeEndingAnimationComplete(bool canceled) {}
+  // complete.
+  virtual void OnOverviewModeEndingAnimationComplete() {}
 
   // Called when the split view mode is about to be started before the window
   // gets snapped and activated).

ash/wm/overview/cleanup_animation_observer.h

@@ -37,8 +37,6 @@ class ASH_EXPORT CleanupAnimationObserver
   void Shutdown() override;
 
  private:
-  FRIEND_TEST_ALL_PREFIXES(WindowSelectorTest, OverviewExitAnimationObserver);
-
   std::unique_ptr<views::Widget> widget_;
   WindowSelectorDelegate* owner_;
 

ash/wm/overview/cleanup_animation_observer_unittest.cc

@@ -8,7 +8,6 @@
 
 #include "ash/test/ash_test_base.h"
 #include "ash/wm/overview/window_selector_delegate.h"
-#include "base/containers/unique_ptr_adapters.h"
 #include "ui/aura/window.h"
 #include "ui/compositor/layer_animation_observer.h"
 #include "ui/compositor/scoped_animation_duration_scale_mode.h"
@@ -42,14 +41,22 @@ class TestWindowSelectorDelegate : public WindowSelectorDelegate {
 
   void RemoveAndDestroyAnimationObserver(
       DelayedAnimationObserver* animation_observer) override {
-    base::EraseIf(observers_, base::MatchesUniquePtr(animation_observer));
+    class IsEqual {
+     public:
+      explicit IsEqual(DelayedAnimationObserver* animation_observer)
+          : animation_observer_(animation_observer) {}
+      bool operator()(const std::unique_ptr<DelayedAnimationObserver>& other) {
+        return (other.get() == animation_observer_);
+      }
+
+     private:
+      const DelayedAnimationObserver* animation_observer_;
+    };
+    observers_.erase(std::remove_if(observers_.begin(), observers_.end(),
+                                    IsEqual(animation_observer)),
+                     observers_.end());
   }
 
-  void AddStartAnimationObserver(
-      std::unique_ptr<DelayedAnimationObserver> animation_observer) override {}
-  void RemoveAndDestroyStartAnimationObserver(
-      DelayedAnimationObserver* animation_observer) override {}
-
  private:
   std::vector<std::unique_ptr<DelayedAnimationObserver>> observers_;
 
@@ -71,7 +78,7 @@ class CleanupAnimationObserverTest : public AshTestBase,
   // cause a window to be closed via
   // views::Widget::GetWidgetForNativeView(window)->Close().
   std::unique_ptr<views::Widget> CreateWindowWidget(const gfx::Rect& bounds) {
-    auto widget = std::make_unique<views::Widget>();
+    std::unique_ptr<views::Widget> widget(new views::Widget);
     views::Widget::InitParams params;
     params.bounds = bounds;
     params.type = views::Widget::InitParams::TYPE_WINDOW;
@@ -103,8 +110,10 @@ class CleanupAnimationObserverTest : public AshTestBase,
 // Tests that basic create-destroy sequence does not crash.
 TEST_F(CleanupAnimationObserverTest, CreateDestroy) {
   TestWindowSelectorDelegate delegate;
-  std::unique_ptr<views::Widget> widget = CreateWindowWidget(gfx::Rect(40, 40));
-  auto observer = std::make_unique<CleanupAnimationObserver>(std::move(widget));
+  std::unique_ptr<views::Widget> widget(
+      CreateWindowWidget(gfx::Rect(0, 0, 40, 40)));
+  std::unique_ptr<CleanupAnimationObserver> observer(
+      new CleanupAnimationObserver(std::move(widget)));
   delegate.AddDelayedAnimationObserver(std::move(observer));
 }
 
@@ -113,7 +122,8 @@ TEST_F(CleanupAnimationObserverTest, CreateDestroy) {
 // owns the observer does not crash.
 TEST_F(CleanupAnimationObserverTest, CreateAnimateComplete) {
   TestWindowSelectorDelegate delegate;
-  std::unique_ptr<views::Widget> widget = CreateWindowWidget(gfx::Rect(40, 40));
+  std::unique_ptr<views::Widget> widget(
+      CreateWindowWidget(gfx::Rect(0, 0, 40, 40)));
   aura::Window* widget_window = widget->GetNativeWindow();
   {
     ui::ScopedLayerAnimationSettings animation_settings(
@@ -123,8 +133,8 @@ TEST_F(CleanupAnimationObserverTest, CreateAnimateComplete) {
     animation_settings.SetPreemptionStrategy(
         ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
 
-    auto observer =
-        std::make_unique<CleanupAnimationObserver>(std::move(widget));
+    std::unique_ptr<CleanupAnimationObserver> observer(
+        new CleanupAnimationObserver(std::move(widget)));
     animation_settings.AddObserver(observer.get());
     delegate.AddDelayedAnimationObserver(std::move(observer));
 
@@ -143,7 +153,8 @@ TEST_F(CleanupAnimationObserverTest, CreateAnimateComplete) {
 // instance in destructor, this test would have crashed.
 TEST_F(CleanupAnimationObserverTest, CreateAnimateShutdown) {
   TestWindowSelectorDelegate delegate;
-  std::unique_ptr<views::Widget> widget = CreateWindowWidget(gfx::Rect(40, 40));
+  std::unique_ptr<views::Widget> widget(
+      CreateWindowWidget(gfx::Rect(0, 0, 40, 40)));
   aura::Window* widget_window = widget->GetNativeWindow();
   {
     // Normal animations for tests have ZERO_DURATION, make sure we are actually
@@ -157,8 +168,8 @@ TEST_F(CleanupAnimationObserverTest, CreateAnimateShutdown) {
     animation_settings.SetPreemptionStrategy(
         ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
 
-    auto observer =
-        std::make_unique<CleanupAnimationObserver>(std::move(widget));
+    std::unique_ptr<CleanupAnimationObserver> observer(
+        new CleanupAnimationObserver(std::move(widget)));
     animation_settings.AddObserver(observer.get());
     delegate.AddDelayedAnimationObserver(std::move(observer));
 

ash/wm/overview/scoped_transform_overview_window.cc

@@ -13,10 +13,8 @@
 #include "ash/wm/overview/drop_target_view.h"
 #include "ash/wm/overview/overview_utils.h"
 #include "ash/wm/overview/scoped_overview_animation_settings.h"
-#include "ash/wm/overview/start_animation_observer.h"
 #include "ash/wm/overview/window_grid.h"
 #include "ash/wm/overview/window_selector.h"
-#include "ash/wm/overview/window_selector_controller.h"
 #include "ash/wm/overview/window_selector_item.h"
 #include "ash/wm/window_mirror_view.h"
 #include "ash/wm/window_state.h"
@@ -271,16 +269,6 @@ void ScopedTransformOverviewWindow::BeginScopedAnimation(
     auto settings = std::make_unique<ScopedOverviewAnimationSettings>(
         animation_type, window);
     settings->DeferPaint();
-
-    // Create a start animation observer if this is an enter overview layout
-    // animation.
-    if (animation_type == OVERVIEW_ANIMATION_LAY_OUT_SELECTOR_ITEMS_ON_ENTER) {
-      auto start_observer = std::make_unique<StartAnimationObserver>();
-      settings->AddObserver(start_observer.get());
-      Shell::Get()->window_selector_controller()->AddStartAnimationObserver(
-          std::move(start_observer));
-    }
-
     animation_settings->push_back(std::move(settings));
   }
 

ash/wm/overview/start_animation_observer.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 "ash/wm/overview/start_animation_observer.h"
-
-namespace ash {
-
-StartAnimationObserver::StartAnimationObserver() = default;
-
-StartAnimationObserver::~StartAnimationObserver() = default;
-
-void StartAnimationObserver::OnImplicitAnimationsCompleted() {
-  if (owner_)
-    owner_->RemoveAndDestroyStartAnimationObserver(this);
-}
-
-void StartAnimationObserver::SetOwner(WindowSelectorDelegate* owner) {
-  DCHECK(!owner_);
-  owner_ = owner;
-}
-
-void StartAnimationObserver::Shutdown() {
-  owner_ = nullptr;
-}
-
-}  // namespace ash
\ No newline at end of file

ash/wm/overview/start_animation_observer.h

-// 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.
-
-#ifndef ASH_WM_OVERVIEW_START_ANIMATION_OBSERVER_H_
-#define ASH_WM_OVERVIEW_START_ANIMATION_OBSERVER_H_
-
-#include "ash/wm/overview/window_selector_delegate.h"
-#include "base/macros.h"
-#include "ui/compositor/layer_animation_observer.h"
-
-namespace ash {
-
-// An observer which watches a overview start animation and signals its owner
-// when the animation it is watching finishes.
-class StartAnimationObserver : public ui::ImplicitAnimationObserver,
-                               public DelayedAnimationObserver {
- public:
-  StartAnimationObserver();
-  ~StartAnimationObserver() override;
-
-  // ui::ImplicitAnimationObserver:
-  void OnImplicitAnimationsCompleted() override;
-
-  // DelayedAnimationObserver:
-  void SetOwner(WindowSelectorDelegate* owner) override;
-  void Shutdown() override;
-
- private:
-  WindowSelectorDelegate* owner_ = nullptr;
-
-  DISALLOW_COPY_AND_ASSIGN(StartAnimationObserver);
-};
-
-}  // namespace ash
-
-#endif  // ASH_WM_OVERVIEW_START_ANIMATION_OBSERVER_H_
\ No newline at end of file

ash/wm/overview/start_animation_observer_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 "ash/wm/overview/start_animation_observer.h"
-
-#include <vector>
-
-#include "ash/test/ash_test_base.h"
-#include "ash/wm/overview/window_selector_delegate.h"
-#include "base/containers/unique_ptr_adapters.h"
-#include "ui/aura/window.h"
-#include "ui/compositor/scoped_layer_animation_settings.h"
-#include "ui/gfx/transform.h"
-
-namespace ash {
-
-namespace {
-
-class TestWindowSelectorDelegate : public WindowSelectorDelegate {
- public:
-  TestWindowSelectorDelegate() = default;
-
-  ~TestWindowSelectorDelegate() override = default;
-
-  // WindowSelectorDelegate:
-  void OnSelectionEnded() override {}
-  void AddDelayedAnimationObserver(
-      std::unique_ptr<DelayedAnimationObserver> animation_observer) override {}
-  void RemoveAndDestroyAnimationObserver(
-      DelayedAnimationObserver* animation_observer) override {}
-  void AddStartAnimationObserver(
-      std::unique_ptr<DelayedAnimationObserver> animation_observer) override {
-    animation_observer->SetOwner(this);
-    observers_.push_back(std::move(animation_observer));
-  }
-  void RemoveAndDestroyStartAnimationObserver(
-      DelayedAnimationObserver* animation_observer) override {
-    base::EraseIf(observers_, base::MatchesUniquePtr(animation_observer));
-  }
-
-  size_t NumObservers() const { return observers_.size(); }
-
- private:
-  std::vector<std::unique_ptr<DelayedAnimationObserver>> observers_;
-
-  DISALLOW_COPY_AND_ASSIGN(TestWindowSelectorDelegate);
-};
-
-}  // namespace
-
-using StartAnimationObserverTest = AshTestBase;
-
-// Tests that adding a StartAnimationObserver works as intended.
-TEST_F(StartAnimationObserverTest, Basic) {
-  TestWindowSelectorDelegate delegate;
-  std::unique_ptr<aura::Window> window = CreateTestWindow();
-
-  {
-    ui::ScopedLayerAnimationSettings animation_settings(
-        window->layer()->GetAnimator());
-    animation_settings.SetTransitionDuration(
-        base::TimeDelta::FromMilliseconds(1000));
-    animation_settings.SetPreemptionStrategy(
-        ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
-
-    auto observer = std::make_unique<StartAnimationObserver>();
-    animation_settings.AddObserver(observer.get());
-    delegate.AddStartAnimationObserver(std::move(observer));
-    window->SetTransform(gfx::Transform(1.f, 0.f, 0.f, 1.f, 100.f, 0.f));
-    EXPECT_EQ(1u, delegate.NumObservers());
-  }
-
-  // Tests that when done animating, the observer count is zero.
-  window->layer()->GetAnimator()->StopAnimating();
-  EXPECT_EQ(0u, delegate.NumObservers());
-}
-
-}  // namespace ash
\ No newline at end of file

ash/wm/overview/window_selector_controller.cc

@@ -325,10 +325,6 @@ bool WindowSelectorController::ToggleOverview(
     // Clear any animations that may be running from last overview end.
     for (const auto& animation : delayed_animations_)
       animation->Shutdown();
-    if (!delayed_animations_.empty()) {
-      Shell::Get()->NotifyOverviewModeStartingAnimationComplete(
-          /*canceled=*/true);
-    }
     delayed_animations_.clear();
 
     window_selector_ = std::make_unique<WindowSelector>(this);
@@ -479,12 +475,6 @@ WindowSelectorController::GetWindowsListInOverviewGridsForTesting() {
 void WindowSelectorController::OnSelectionEnded() {
   if (is_shutting_down_)
     return;
-
-  if (!start_animations_.empty()) {
-    Shell::Get()->NotifyOverviewModeEndingAnimationComplete(
-        /*canceled=*/true);
-  }
-  start_animations_.clear();
   is_shutting_down_ = true;
   Shell::Get()->NotifyOverviewModeEnding();
   auto* window_selector = window_selector_.release();
@@ -518,24 +508,7 @@ void WindowSelectorController::RemoveAndDestroyAnimationObserver(
   if (!window_selector_ && !previous_empty && delayed_animations_.empty()) {
     if (IsBlurAllowed())
       overview_blur_controller_->Unblur();
-    Shell::Get()->NotifyOverviewModeEndingAnimationComplete(/*canceled=*/false);
-  }
-}
-
-void WindowSelectorController::AddStartAnimationObserver(
-    std::unique_ptr<DelayedAnimationObserver> animation_observer) {
-  animation_observer->SetOwner(this);
-  start_animations_.push_back(std::move(animation_observer));
-}
-
-void WindowSelectorController::RemoveAndDestroyStartAnimationObserver(
-    DelayedAnimationObserver* animation_observer) {
-  const bool previous_empty = start_animations_.empty();
-  base::EraseIf(start_animations_, base::MatchesUniquePtr(animation_observer));
-
-  if (!previous_empty && start_animations_.empty()) {
-    Shell::Get()->NotifyOverviewModeStartingAnimationComplete(
-        /*canceled=*/false);
+    Shell::Get()->NotifyOverviewModeEndingAnimationComplete();
   }
 }
 

ash/wm/overview/window_selector_controller.h

@@ -22,11 +22,6 @@ class WindowSelectorTest;
 // allows selecting a window to activate it.
 class ASH_EXPORT WindowSelectorController : public WindowSelectorDelegate {
  public:
-  enum class AnimationCompleteReason {
-    kCompleted,
-    kCanceled,
-  };
-
   WindowSelectorController();
   ~WindowSelectorController() override;
 
@@ -77,10 +72,6 @@ class ASH_EXPORT WindowSelectorController : public WindowSelectorDelegate {
       std::unique_ptr<DelayedAnimationObserver> animation) override;
   void RemoveAndDestroyAnimationObserver(
       DelayedAnimationObserver* animation) override;
-  void AddStartAnimationObserver(
-      std::unique_ptr<DelayedAnimationObserver> animation_observer) override;
-  void RemoveAndDestroyStartAnimationObserver(
-      DelayedAnimationObserver* animation_observer) override;
 
   WindowSelector* window_selector() { return window_selector_.get(); }
 
@@ -89,7 +80,6 @@ class ASH_EXPORT WindowSelectorController : public WindowSelectorDelegate {
   friend class WindowSelectorTest;
   FRIEND_TEST_ALL_PREFIXES(TabletModeControllerTest,
                            DisplayDisconnectionDuringOverview);
-  FRIEND_TEST_ALL_PREFIXES(WindowSelectorTest, OverviewExitAnimationObserver);
 
   // There is no need to blur or unblur the wallpaper for tests.
   static void SetDoNotChangeWallpaperBlurForTests();
@@ -102,10 +92,6 @@ class ASH_EXPORT WindowSelectorController : public WindowSelectorDelegate {
   // those animations are in progress, the animations are shut down and the
   // widgets destroyed.
   std::vector<std::unique_ptr<DelayedAnimationObserver>> delayed_animations_;
-  // Collection of DelayedAnimationObserver objects. When this becomes empty,
-  // notify shell that the starting animations have been completed.
-  std::vector<std::unique_ptr<DelayedAnimationObserver>> start_animations_;
-
   std::unique_ptr<WindowSelector> window_selector_;
   base::Time last_selection_time_;
 

ash/wm/overview/window_selector_delegate.h

@@ -5,8 +5,6 @@
 #ifndef ASH_WM_OVERVIEW_WINDOW_SELECTOR_DELEGATE_H_
 #define ASH_WM_OVERVIEW_WINDOW_SELECTOR_DELEGATE_H_
 
-#include <memory>
-
 #include "ash/ash_export.h"
 #include "base/compiler_specific.h"
 
@@ -39,24 +37,14 @@ class ASH_EXPORT WindowSelectorDelegate {
       std::unique_ptr<DelayedAnimationObserver> animation_observer) = 0;
 
   // Finds and erases |animation_observer| from the list deleting the widget
-  // owned by the |animation_observer|. This method should be called when a
-  // scheduled animation completes. If the animation completion callback is a
-  // result of a window getting destroyed then the
-  // DelayedAnimationObserver::Shutdown() should be called first before
-  // destroying the window.
+  // owned by the |animation_observer|.
+  // This method should be called when a scheduled animation completes.
+  // If the animation completion callback is a result of a window getting
+  // destroyed then the DelayedAnimationObserver::Shutdown() should be called
+  // first before destroying the window.
   virtual void RemoveAndDestroyAnimationObserver(
       DelayedAnimationObserver* animation_observer) = 0;
 
-  // Passes ownership of |animation_observer| to |this| delegate.
-  virtual void AddStartAnimationObserver(
-      std::unique_ptr<DelayedAnimationObserver> animation_observer) = 0;
-
-  // Finds and erases |animation_observer| from the list which tracks the start
-  // animations. This method should be called when a scheduled start overview
-  // animation completes.
-  virtual void RemoveAndDestroyStartAnimationObserver(
-      DelayedAnimationObserver* animation_observer) = 0;
-
  protected:
   virtual ~WindowSelectorDelegate() {}
 };

ash/wm/overview/window_selector_item.cc

@@ -18,7 +18,6 @@
 #include "ash/wm/overview/rounded_rect_view.h"
 #include "ash/wm/overview/scoped_overview_animation_settings.h"
 #include "ash/wm/overview/scoped_transform_overview_window.h"
-#include "ash/wm/overview/start_animation_observer.h"
 #include "ash/wm/overview/window_grid.h"
 #include "ash/wm/overview/window_selector_controller.h"
 #include "ash/wm/splitview/split_view_constants.h"
@@ -1180,16 +1179,6 @@ void WindowSelectorItem::UpdateHeaderLayout(
       mode == HeaderFadeInMode::kFirstUpdate ? OVERVIEW_ANIMATION_NONE
                                              : animation_type,
       widget_window);
-
-  // Create a start animation observer if this is an enter overview layout
-  // animation.
-  if (animation_type == OVERVIEW_ANIMATION_LAY_OUT_SELECTOR_ITEMS_ON_ENTER) {
-    auto start_observer = std::make_unique<StartAnimationObserver>();
-    animation_settings.AddObserver(start_observer.get());
-    Shell::Get()->window_selector_controller()->AddStartAnimationObserver(
-        std::move(start_observer));
-  }
-
   // |widget_window| covers both the transformed window and the header
   // as well as the gap between the windows to prevent events from reaching
   // the window including its sizing borders.

ash/wm/overview/window_selector_unittest.cc

@@ -28,7 +28,6 @@
 #include "ash/system/tray/system_tray.h"
 #include "ash/system/unified/unified_system_tray.h"
 #include "ash/test/ash_test_base.h"
-#include "ash/wm/overview/cleanup_animation_observer.h"
 #include "ash/wm/overview/overview_utils.h"
 #include "ash/wm/overview/overview_window_drag_controller.h"
 #include "ash/wm/overview/window_grid.h"
@@ -3109,25 +3108,19 @@ namespace {
 // Test class that allows us to check what whether the last overview enter or
 // exit was using a slide animation. This is needed because the cached slide
 // animation variable may be reset or the WindowSelector object may not be
-// available after a toggle has completed. Also stores whether the animation
-// complete observers fired because an animation completed or was canceled.
-class TestOverviewObserver : public ShellObserver {
+// available after a toggle has completed.
+class TestOverviewAnimationTypeObserver : public ShellObserver {
  public:
-  TestOverviewObserver() { Shell::Get()->AddShellObserver(this); }
-  ~TestOverviewObserver() override { Shell::Get()->RemoveShellObserver(this); }
+  TestOverviewAnimationTypeObserver() { Shell::Get()->AddShellObserver(this); }
+  ~TestOverviewAnimationTypeObserver() override {
+    Shell::Get()->RemoveShellObserver(this);
+  }
 
   // ShellObserver:
   void OnOverviewModeStarting() override { UpdateLastAnimationWasSlide(); }
   void OnOverviewModeEnding() override { UpdateLastAnimationWasSlide(); }
-  void OnOverviewModeStartingAnimationComplete(bool canceled) override {
-    animation_canceled_ = canceled;
-  }
-  void OnOverviewModeEndingAnimationComplete(bool canceled) override {
-    animation_canceled_ = canceled;
-  }
 
   bool last_animation_was_slide() const { return last_animation_was_slide_; }
-  bool animation_canceled() const { return animation_canceled_; }
 
  private:
   void UpdateLastAnimationWasSlide() {
@@ -3140,19 +3133,18 @@ class TestOverviewObserver : public ShellObserver {
   }
 
   bool last_animation_was_slide_ = false;
-  bool animation_canceled_ = false;
 
-  DISALLOW_COPY_AND_ASSIGN(TestOverviewObserver);
+  DISALLOW_COPY_AND_ASSIGN(TestOverviewAnimationTypeObserver);
 };
 
 }  // namespace
 
 // Tests the slide animation for overview is never used in clamshell.
 TEST_F(WindowSelectorTest, OverviewEnterExitAnimation) {
-  TestOverviewObserver observer;
+  TestOverviewAnimationTypeObserver observer;
 
   const gfx::Rect bounds(200, 200);
-  std::unique_ptr<aura::Window> window(CreateWindow(bounds));
+  std::unique_ptr<aura::Window> window1(CreateWindow(bounds));
 
   ToggleOverview();
   EXPECT_FALSE(observer.last_animation_was_slide());
@@ -3162,7 +3154,7 @@ TEST_F(WindowSelectorTest, OverviewEnterExitAnimation) {
 
   // Even with all window minimized, there should not be a slide animation.
   ASSERT_FALSE(IsSelecting());
-  wm::GetWindowState(window.get())->Minimize();
+  wm::GetWindowState(window1.get())->Minimize();
   ToggleOverview();
   EXPECT_FALSE(observer.last_animation_was_slide());
 }
@@ -3171,7 +3163,7 @@ TEST_F(WindowSelectorTest, OverviewEnterExitAnimation) {
 // are minimized, and that if overview is exited from the home launcher all
 // windows are minimized.
 TEST_F(WindowSelectorTest, OverviewEnterExitAnimationTablet) {
-  TestOverviewObserver observer;
+  TestOverviewAnimationTypeObserver observer;
 
   // Ensure calls to EnableTabletModeWindowManager complete.
   base::RunLoop().RunUntilIdle();
@@ -3179,7 +3171,7 @@ TEST_F(WindowSelectorTest, OverviewEnterExitAnimationTablet) {
   base::RunLoop().RunUntilIdle();
 
   const gfx::Rect bounds(200, 200);
-  std::unique_ptr<aura::Window> window(CreateWindow(bounds));
+  std::unique_ptr<aura::Window> window1(CreateWindow(bounds));
 
   ToggleOverview();
   EXPECT_FALSE(observer.last_animation_was_slide());
@@ -3189,77 +3181,13 @@ TEST_F(WindowSelectorTest, OverviewEnterExitAnimationTablet) {
   ToggleOverview(WindowSelector::EnterExitOverviewType::kWindowsMinimized);
   EXPECT_TRUE(observer.last_animation_was_slide());
   ASSERT_FALSE(IsSelecting());
-  EXPECT_TRUE(wm::GetWindowState(window.get())->IsMinimized());
+  EXPECT_TRUE(wm::GetWindowState(window1.get())->IsMinimized());
 
   // All windows are minimized, so we should use the slide animation.
   ToggleOverview();
   EXPECT_TRUE(observer.last_animation_was_slide());
 }
 
-// Tests that the overview enter animation observer works as expected.
-TEST_F(WindowSelectorTest, OverviewEnterAnimationObserver) {
-  TestOverviewObserver observer;
-
-  ui::ScopedAnimationDurationScaleMode animation_scale_mode(
-      ui::ScopedAnimationDurationScaleMode::NON_ZERO_DURATION);
-
-  const gfx::Rect bounds(200, 200);
-  std::unique_ptr<aura::Window> window(CreateWindow(bounds));
-
-  // Test that if the animations are allowed to run out on enter the observer
-  // will be notified of complete animations.
-  ToggleOverview();
-  WindowSelectorItem* item = GetWindowItemForWindow(0, window.get());
-  window->layer()->GetAnimator()->StopAnimating();
-  item_widget(item)->GetNativeWindow()->layer()->GetAnimator()->StopAnimating();
-  EXPECT_FALSE(observer.animation_canceled());
-
-  ToggleOverview();
-
-  // Test that if the animations are canceled after entering by exiting overview
-  // right away, the observer will be notified of incomplete animations.
-  ToggleOverview();
-  ToggleOverview();
-  EXPECT_TRUE(observer.animation_canceled());
-}
-
-// Tests that the overview exit animation observer works as expected.
-TEST_F(WindowSelectorTest, OverviewExitAnimationObserver) {
-  TestOverviewObserver observer;
-
-  ui::ScopedAnimationDurationScaleMode animation_scale_mode(
-      ui::ScopedAnimationDurationScaleMode::NON_ZERO_DURATION);
-
-  const gfx::Rect bounds(200, 200);
-  std::unique_ptr<aura::Window> window(CreateWindow(bounds));
-
-  ToggleOverview();
-
-  // Test that if the animations are allowed to run out on exit the observer
-  // will be notified of complete animations.
-  ToggleOverview();
-  window->layer()->GetAnimator()->StopAnimating();
-  std::vector<std::unique_ptr<DelayedAnimationObserver>>& delayed_animations =
-      window_selector_controller()->delayed_animations_;
-  // On animation complete |delayed_animations| will erase its own members, so
-  // use a while loop to avoid indexing errors.
-  ASSERT_FALSE(delayed_animations.empty());
-  while (!delayed_animations.empty()) {
-    views::Widget* item_widget =
-        static_cast<CleanupAnimationObserver*>(delayed_animations.back().get())
-            ->widget_.get();
-    item_widget->GetNativeWindow()->layer()->GetAnimator()->StopAnimating();
-  }
-  EXPECT_FALSE(observer.animation_canceled());
-
-  // Test that if the animations are canceled after exiting by reentering
-  // overview right away, the observer will be notified of incomplete
-  // animations.
-  ToggleOverview();
-  ToggleOverview();
-  EXPECT_TRUE(observer.animation_canceled());
-}
-
 // Tests that overview mode is entered with kWindowDragged mode when an app is
 // dragged from the top of the screen.
 TEST_F(WindowSelectorTest, DraggingFromTopAnimation) {