overview: Fix issues with minimized windows in overview.

The minimized windows are now stacked underneath non-minimized windows.
Minimized windows now animate back when uncessfully swipe to close.

Test: manual
Bug: 886392, 886390
Change-Id: I520a9cfc642e5f417af6755b783b831098430ce8
Reviewed-on: https://chromium-review.googlesource.com/1238782
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Reviewed-by: Xiaoqian Dai <xdai@chromium.org>
Cr-Commit-Position: refs/heads/master@{#593590}

ash/wm/overview/scoped_transform_overview_window.cc

@@ -526,6 +526,10 @@ void ScopedTransformOverviewWindow::CreateMirrorWindowForMinimizedState() {
   minimized_widget_->SetBounds(bounds);
   minimized_widget_->Show();
 
+  // Stack the minimized window at the bottom since it is never transformed in
+  // and only faded in, so it should always be underneath non minimized windows.
+  window_->parent()->StackChildAtBottom(minimized_widget_->GetNativeWindow());
+
   FadeInWidgetAndMaybeSlideOnEnter(
       minimized_widget_.get(), OVERVIEW_ANIMATION_ENTER_OVERVIEW_MODE_FADE_IN,
       /*slide=*/false);

ash/wm/overview/window_selector_item.cc

@@ -633,8 +633,14 @@ void WindowSelectorItem::SetBounds(const gfx::Rect& target_bounds,
 
   gfx::Rect inset_bounds(target_bounds);
   inset_bounds.Inset(kWindowMargin, kWindowMargin);
-  if (wm::GetWindowState(GetWindow())->IsMinimized())
+
+  // Do not animate if entering when the window is minimized, as it will be
+  // faded in. We still want to animate if the position is changed after
+  // entering.
+  if (wm::GetWindowState(GetWindow())->IsMinimized() &&
+      mode == HeaderFadeInMode::kFirstUpdate) {
     new_animation_type = OVERVIEW_ANIMATION_NONE;
+  }
 
   SetItemBounds(inset_bounds, new_animation_type);
 

ash/wm/overview/window_selector_unittest.cc

@@ -2612,13 +2612,14 @@ TEST_F(WindowSelectorTest, OverviewWidgetStackingOrder) {
 
   // The original order of stacking is determined by the order the associated
   // window was activated (created in this case). All widgets associated with
-  // minimized windows will be above non minimized windows, because a widget for
-  // the minimized windows is created upon entering overview, and them the
-  // window selector item widget is stacked on top of that.
-  EXPECT_GT(IndexOf(widget2->GetNativeWindow(), parent),
-            IndexOf(widget3->GetNativeWindow(), parent));
+  // minimized windows will be below non minimized windows, because a widget for
+  // the minimized windows is created upon entering overview, and they are
+  // explicitly stacked beneath non minimized windows so they do not cover them
+  // during enter animation.
   EXPECT_GT(IndexOf(widget3->GetNativeWindow(), parent),
             IndexOf(widget1->GetNativeWindow(), parent));
+  EXPECT_GT(IndexOf(widget1->GetNativeWindow(), parent),
+            IndexOf(widget2->GetNativeWindow(), parent));
 
   // Verify that only minimized windows have minimized widgets in overview.
   EXPECT_FALSE(min_widget1);
@@ -2660,10 +2661,10 @@ TEST_F(WindowSelectorTest, OverviewWidgetStackingOrder) {
   generator->ReleaseLeftButton();
 
   // Verify the stacking order is same as before dragging started.
-  EXPECT_GT(IndexOf(widget2->GetNativeWindow(), parent),
-            IndexOf(widget3->GetNativeWindow(), parent));
   EXPECT_GT(IndexOf(widget3->GetNativeWindow(), parent),
             IndexOf(widget1->GetNativeWindow(), parent));
+  EXPECT_GT(IndexOf(widget1->GetNativeWindow(), parent),
+            IndexOf(widget2->GetNativeWindow(), parent));
 }
 
 // Tests that overview widgets are stacked in the correct order.