Use correct fade animation when entering overview from home

And add some delay before stating opacity animation.

BUG=1020735

Change-Id: I5fabd3923c55ecf969727b2887e32dd938873b41
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1895080Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Commit-Queue: Toni Baržić <tbarzic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#712347}

ash/wm/overview/overview_item.cc

@@ -457,9 +457,14 @@ void OverviewItem::SetBounds(const gfx::RectF& target_bounds,
               overview_session_->enter_exit_overview_type() ==
               OverviewSession::EnterExitOverviewType::kSlideInEnter;
           if (!slide_in) {
-            FadeInWidgetAndMaybeSlideOnEnter(
-                item_widget_.get(),
-                OVERVIEW_ANIMATION_ENTER_OVERVIEW_MODE_FADE_IN,
+            // If entering from home launcher, use the home specific (fade)
+            // animation.
+            OverviewAnimationType fade_animation =
+                animation_type == OVERVIEW_ANIMATION_ENTER_FROM_HOME_LAUNCHER
+                    ? animation_type
+                    : OVERVIEW_ANIMATION_ENTER_OVERVIEW_MODE_FADE_IN;
+
+            FadeInWidgetAndMaybeSlideOnEnter(item_widget_.get(), fade_animation,
                                              /*slide=*/false,
                                              /*observe=*/true);
           }

ash/wm/overview/scoped_overview_animation_settings.cc

@@ -158,10 +158,14 @@ ScopedOverviewAnimationSettings::ScopedOverviewAnimationSettings(
       animation_settings_->SetTweenType(gfx::Tween::FAST_OUT_SLOW_IN);
       animation_settings_->SetPreemptionStrategy(
           ui::LayerAnimator::ENQUEUE_NEW_ANIMATION);
-      // Add animation delay when entering from home launcher using slide
-      // animation (which is the case if homerview gesture is not enabled, in
-      // which case overview will fade in without sliding).
-      if (!features::IsHomerviewGestureEnabled()) {
+      // Add animation delay when entering from home launcher.
+      // Delay transform only when using slide animation (which is used
+      // if kHomerviewGesture is not enabled), as otherwise the overview item
+      // will only fade in.
+      if (features::IsHomerviewGestureEnabled()) {
+        animator->SchedulePauseForProperties(
+            kFromHomeLauncherDelay, ui::LayerAnimationElement::OPACITY);
+      } else {
         animator->SchedulePauseForProperties(
             kFromHomeLauncherDelay, ui::LayerAnimationElement::OPACITY |
                                         ui::LayerAnimationElement::TRANSFORM);