bento: Zero state of desks

See demo at the crbug.

Bug: 1158583
Change-Id: I7ee3ff75c2126543a2fe215817281c11540d080a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2604683Reviewed-by: Ahmed Fakhry <afakhry@chromium.org>
Commit-Queue: Min Chen <minch@chromium.org>
Cr-Commit-Position: refs/heads/master@{#843211}

ash/BUILD.gn

@@ -1516,10 +1516,14 @@ component("ash") {
     "wm/desks/desks_restore_util.cc",
     "wm/desks/desks_restore_util.h",
     "wm/desks/desks_util.cc",
+    "wm/desks/expanded_state_new_desk_button.cc",
+    "wm/desks/expanded_state_new_desk_button.h",
     "wm/desks/new_desk_button.cc",
     "wm/desks/new_desk_button.h",
     "wm/desks/root_window_desk_switch_animator.cc",
     "wm/desks/root_window_desk_switch_animator.h",
+    "wm/desks/zero_state_button.cc",
+    "wm/desks/zero_state_button.h",
     "wm/drag_details.cc",
     "wm/drag_details.h",
     "wm/drag_window_controller.cc",

ash/wm/desks/desk_mini_view_animations.cc

@@ -6,9 +6,11 @@
 
 #include <utility>
 
+#include "ash/public/cpp/ash_features.h"
 #include "ash/shell.h"
 #include "ash/wm/desks/desk_mini_view.h"
 #include "ash/wm/desks/desks_bar_view.h"
+#include "ash/wm/desks/expanded_state_new_desk_button.h"
 #include "ash/wm/overview/overview_controller.h"
 #include "ash/wm/overview/overview_session.h"
 #include "ui/compositor/layer.h"
@@ -41,18 +43,22 @@ void InitScopedAnimationSettings(ui::ScopedLayerAnimationSettings* settings,
       ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
 }
 
-// Animates the transforms of the layers of the given |mini_views| from the
-// supplied |begin_transform| to the identity transform.
-void AnimateMiniViews(std::vector<DeskMiniView*> mini_views,
-                      const gfx::Transform& begin_transform) {
-  for (auto* mini_view : mini_views) {
-    ui::Layer* layer = mini_view->layer();
+// Animates the transform of the layer of the given |view| from the supplied
+// |begin_transform| to the identity transform.
+void AnimateView(views::View* view, const gfx::Transform& begin_transform) {
+  ui::Layer* layer = view->layer();
   layer->SetTransform(begin_transform);
 
   ui::ScopedLayerAnimationSettings settings{layer->GetAnimator()};
   InitScopedAnimationSettings(&settings, kExistingMiniViewsAnimationDuration);
   layer->SetTransform(kEndTransform);
-  }
+}
+
+// See details at AnimateView.
+void AnimateMiniViews(std::vector<DeskMiniView*> mini_views,
+                      const gfx::Transform& begin_transform) {
+  for (auto* mini_view : mini_views)
+    AnimateView(mini_view, begin_transform);
 }
 
 // A self-deleting object that performs a fade out animation on
@@ -129,12 +135,25 @@ void PerformNewDeskMiniViewAnimation(
       layer->SetOpacity(1);
     layer->SetTransform(kEndTransform);
   }
+
+  // The new desk button in the expanded desks bar moves at the opposite
+  // direction of the existing mini views while creating a new mini view. The
+  // existing mini views will move from right to left while the new desk button
+  // will move from left to right. Since the newly added mini view will be added
+  // between the last mini view and the new desk button.
+  if (features::IsBentoEnabled()) {
+    gfx::Transform new_desk_button_begin_transform;
+    new_desk_button_begin_transform.Translate(-shift_x, 0);
+    AnimateView(bar_view->expanded_state_new_desk_button(),
+                new_desk_button_begin_transform);
+  }
 }
 
 void PerformRemoveDeskMiniViewAnimation(
     DeskMiniView* removed_mini_view,
     std::vector<DeskMiniView*> mini_views_left,
     std::vector<DeskMiniView*> mini_views_right,
+    ExpandedStateNewDeskButton* expanded_state_new_desk_button,
     int shift_x) {
   gfx::Transform mini_views_left_begin_transform;
   mini_views_left_begin_transform.Translate(shift_x, 0);
@@ -145,6 +164,11 @@ void PerformRemoveDeskMiniViewAnimation(
 
   AnimateMiniViews(mini_views_left, mini_views_left_begin_transform);
   AnimateMiniViews(mini_views_right, mini_views_right_begin_transform);
+
+  if (features::IsBentoEnabled()) {
+    AnimateView(expanded_state_new_desk_button,
+                mini_views_right_begin_transform);
+  }
 }
 
 }  // namespace ash

ash/wm/desks/desk_mini_view_animations.h

@@ -12,6 +12,7 @@ namespace ash {
 
 class DesksBarView;
 class DeskMiniView;
+class ExpandedStateNewDeskButton;
 
 // Animates new desk mini_views, fading them in and moving them from right to
 // left into their final positions in the desk bar view. It will also animate
@@ -39,15 +40,18 @@ void PerformNewDeskMiniViewAnimation(
 // |removed_mini_view| from the views hierarchy and deleting it.
 // |mini_views_left|, and |mini_views_right| are lists of the remaining
 // mini_views to left and to the right of the removed mini_view respectively.
-// Either list can be empty (e.g. if the removed mini_view is the last one on
-// the right). |shift_x| is the amount by which the remaining mini_views will be
-// moved horizontally to occupy the space that the removed mini_view used to
-// occupy. It assumes that the remiaing mini_views have been laid out in their
-// final positions as if the removed mini_view no longer exits.
+// |expanded_state_new_desk_button| will be moved to right the same as
+// |mini_views_right| if Bento is enabled. Either list can be empty (e.g. if the
+// removed mini_view is the last one on the right). |shift_x| is the amount by
+// which the remaining mini_views will be moved horizontally to occupy the space
+// that the removed mini_view used to occupy. It assumes that the remaining
+// mini_views have been laid out in their final positions as if the removed
+// mini_view no longer exists.
 void PerformRemoveDeskMiniViewAnimation(
     DeskMiniView* removed_mini_view,
     std::vector<DeskMiniView*> mini_views_left,
     std::vector<DeskMiniView*> mini_views_right,
+    ExpandedStateNewDeskButton* expanded_state_new_desk_button,
     int shift_x);
 
 }  // namespace ash

ash/wm/desks/desk_preview_view.cc

@@ -26,7 +26,6 @@
 #include "ui/compositor/layer_type.h"
 #include "ui/compositor/paint_recorder.h"
 #include "ui/gfx/canvas.h"
-#include "ui/gfx/geometry/insets.h"
 #include "ui/gfx/geometry/rounded_corners_f.h"
 #include "ui/gfx/geometry/vector2d_f.h"
 #include "ui/gfx/skia_paint_util.h"

ash/wm/desks/desks_bar_view.h

@@ -15,10 +15,13 @@
 
 namespace ash {
 
+class DeskBarHoverObserver;
 class DeskMiniView;
+class ExpandedStateNewDeskButton;
 class NewDeskButton;
-class DeskBarHoverObserver;
 class OverviewGrid;
+class ZeroStateDefaultDeskButton;
+class ZeroStateNewDeskButton;
 
 // A bar that resides at the top portion of the overview mode's ShieldView,
 // which contains the virtual desks mini_views, as well as the new desk button.
@@ -28,6 +31,8 @@ class ASH_EXPORT DesksBarView : public views::View,
   explicit DesksBarView(OverviewGrid* overview_grid);
   ~DesksBarView() override;
 
+  static constexpr int kZeroStateBarHeight = 40;
+
   // Returns the height of the desk bar view which is based on the given |width|
   // of the overview grid that exists on |root| (which is the same as the width
   // of the bar) and |desks_bar_view|'s content (since they may not fit the
@@ -49,6 +54,18 @@ class ASH_EXPORT DesksBarView : public views::View,
 
   NewDeskButton* new_desk_button() const { return new_desk_button_; }
 
+  ZeroStateDefaultDeskButton* zero_state_default_desk_button() const {
+    return zero_state_default_desk_button_;
+  }
+
+  ZeroStateNewDeskButton* zero_state_new_desk_button() const {
+    return zero_state_new_desk_button_;
+  }
+
+  ExpandedStateNewDeskButton* expanded_state_new_desk_button() const {
+    return expanded_state_new_desk_button_;
+  }
+
   const std::vector<DeskMiniView*>& mini_views() const { return mini_views_; }
 
   const gfx::Point& last_dragged_item_screen_location() const {
@@ -82,6 +99,11 @@ class ASH_EXPORT DesksBarView : public views::View,
   void SetDragDetails(const gfx::Point& screen_location,
                       bool dragged_item_over_bar);
 
+  // Returns true if it is in zero state. It is the state of the desks bar when
+  // there's only a single desk available, in which case the bar is shown in a
+  // minimized state.
+  bool IsZeroState() const;
+
   // views::View:
   const char* GetClassName() const override;
   bool OnMousePressed(const ui::MouseEvent& event) override;
@@ -102,12 +124,15 @@ class ASH_EXPORT DesksBarView : public views::View,
   void OnDeskSwitchAnimationLaunching() override;
   void OnDeskSwitchAnimationFinished() override;
 
- private:
-  // This is called on initialization or when a new desk is created to create
-  // the needed new mini_views. If |initializing_bar_view| is false, the
-  // mini_views will be animated to their final positions.
-  void UpdateNewMiniViews(bool initializing_bar_view);
+  // This is called on initialization, creating a new desk through the
+  // NewDeskButton or ExpandedStateNewDeskButton, or expanding from zero state
+  // bar to the expanded desks bar when Bento is enabled. Performs the expanding
+  // animation if |expanding_bar_view| is true, otherwise animates the
+  // mini_views (also the ExpandedStateNewDeskButton if Bento is enabled) to
+  // their final positions if |initializing_bar_view| is false.
+  void UpdateNewMiniViews(bool initializing_bar_view, bool expanding_bar_view);
 
+ private:
   // Returns the mini_view associated with |desk| or nullptr if no mini_view
   // has been created for it yet.
   DeskMiniView* FindMiniViewForDesk(const Desk* desk) const;
@@ -125,10 +150,20 @@ class ASH_EXPORT DesksBarView : public views::View,
   // child if Bento is enabled.
   DeskMiniView* AddMiniViewAsChild(std::unique_ptr<DeskMiniView> mini_view);
 
+  // Updates the visibility of the two buttons inside the zero state desks bar
+  // and the ExpandedStateNewDeskButton on the desk bar's state. Used only when
+  // Bento is enabled.
+  void UpdateBentoDeskButtonsVisibility();
+
+  // Translates the background view and positions windows in overview while
+  // switching between zero state desks bar and expanded desks bar.
+  void SetExpanded(bool expanded);
+
   // A view that shows a dark gary transparent background that can be animated
   // when the very first mini_views are created.
   views::View* background_view_;
 
+  // Used only in classic desks. Will be removed once Bento is fully launched.
   NewDeskButton* new_desk_button_;
 
   // The views representing desks mini_views. They're owned by views hierarchy.
@@ -160,6 +195,11 @@ class ASH_EXPORT DesksBarView : public views::View,
   // |new_desk_button_| currently. Used only when Bento is enabled.
   views::View* scroll_view_contents_ = nullptr;
 
+  // Used only when Bento is enabled.
+  ZeroStateDefaultDeskButton* zero_state_default_desk_button_;
+  ZeroStateNewDeskButton* zero_state_new_desk_button_;
+  ExpandedStateNewDeskButton* expanded_state_new_desk_button_;
+
   DISALLOW_COPY_AND_ASSIGN(DesksBarView);
 };
 

ash/wm/desks/expanded_state_new_desk_button.cc

+// Copyright 2021 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/desks/expanded_state_new_desk_button.h"
+
+#include "ash/resources/vector_icons/vector_icons.h"
+#include "ash/shell.h"
+#include "ash/strings/grit/ash_strings.h"
+#include "ash/style/ash_color_provider.h"
+#include "ash/wm/desks/desk_preview_view.h"
+#include "ash/wm/desks/desks_bar_view.h"
+#include "ash/wm/desks/zero_state_button.h"
+#include "ash/wm/overview/overview_controller.h"
+#include "ash/wm/overview/overview_session.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/gfx/paint_vector_icon.h"
+#include "ui/views/controls/label.h"
+
+namespace ash {
+
+namespace {
+
+constexpr int kNewDeskButtonAndNameSpacing = 8;
+
+// The new desk button in expand desks bar in Bento has the same size as the
+// desk preview, which is proportional to the size of the display on which it
+// resides.
+gfx::Rect GetExpandedStateNewDeskButtonBounds(aura::Window* root_window) {
+  const int preview_height =
+      DeskPreviewView::GetHeight(root_window, /*compact=*/false);
+  const auto root_size = root_window->bounds().size();
+  return gfx::Rect(preview_height * root_size.width() / root_size.height(),
+                   preview_height);
+}
+
+// The button belongs to ExpandedStateNewDeskButton.
+class ASH_EXPORT InnerNewDeskButton : public DeskButtonBase {
+ public:
+  InnerNewDeskButton() : DeskButtonBase(base::string16()) {
+    paint_contents_only_ = true;
+  }
+  InnerNewDeskButton(const InnerNewDeskButton&) = delete;
+  InnerNewDeskButton operator=(const InnerNewDeskButton&) = delete;
+  ~InnerNewDeskButton() override = default;
+
+  // DeskButtonBase:
+  const char* GetClassName() const override { return "InnerNewDeskButton"; }
+
+  void OnThemeChanged() override {
+    DeskButtonBase::OnThemeChanged();
+    AshColorProvider::Get()->DecoratePillButton(this, &kDesksNewDeskButtonIcon);
+    UpdateButtonState();
+  }
+
+  void OnButtonPressed() override {
+    auto* controller = DesksController::Get();
+    if (controller->CanCreateDesks()) {
+      controller->NewDesk(DesksCreationRemovalSource::kButton);
+      UpdateButtonState();
+    }
+  }
+
+  // Update the button's enable/disable state based on current desks state.
+  void UpdateButtonState() override {
+    const bool enabled = DesksController::Get()->CanCreateDesks();
+
+    // Notify the overview highlight if we are about to be disabled.
+    if (!enabled) {
+      OverviewSession* overview_session =
+          Shell::Get()->overview_controller()->overview_session();
+      DCHECK(overview_session);
+      overview_session->highlight_controller()->OnViewDestroyingOrDisabling(
+          this);
+    }
+    SetEnabled(enabled);
+
+    const auto* color_provider = AshColorProvider::Get();
+    background_color_ = color_provider->GetControlsLayerColor(
+        AshColorProvider::ControlsLayerType::kControlBackgroundColorInactive);
+    if (!enabled)
+      background_color_ = AshColorProvider::GetDisabledColor(background_color_);
+
+    SetInkDropVisibleOpacity(
+        color_provider->GetRippleAttributes(background_color_).inkdrop_opacity);
+    SchedulePaint();
+  }
+};
+
+}  // namespace
+
+ExpandedStateNewDeskButton::ExpandedStateNewDeskButton(DesksBarView* bar_view)
+    : bar_view_(bar_view),
+      new_desk_button_(AddChildView(std::make_unique<InnerNewDeskButton>())),
+      label_(AddChildView(std::make_unique<views::Label>())) {
+  SetPaintToLayer();
+  layer()->SetFillsBoundsOpaquely(false);
+
+  label_->SetText(l10n_util::GetStringUTF16(IDS_ASH_DESKS_NEW_DESK_BUTTON));
+  label_->SetHorizontalAlignment(gfx::ALIGN_CENTER);
+}
+
+void ExpandedStateNewDeskButton::Layout() {
+  const gfx::Rect new_desk_button_bounds = GetExpandedStateNewDeskButtonBounds(
+      bar_view_->GetWidget()->GetNativeWindow()->GetRootWindow());
+  new_desk_button_->SetBoundsRect(new_desk_button_bounds);
+
+  const gfx::Size label_size = label_->GetPreferredSize();
+  label_->SetBoundsRect(gfx::Rect(
+      gfx::Point(
+          (new_desk_button_bounds.width() - label_size.width()) / 2,
+          new_desk_button_bounds.bottom() + kNewDeskButtonAndNameSpacing),
+      label_size));
+}
+
+void ExpandedStateNewDeskButton::UpdateButtonState() {
+  new_desk_button_->UpdateButtonState();
+}
+
+}  // namespace ash

ash/wm/desks/expanded_state_new_desk_button.h

+// Copyright 2021 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_DESKS_EXPANDED_STATE_NEW_DESK_BUTTON_H_
+#define ASH_WM_DESKS_EXPANDED_STATE_NEW_DESK_BUTTON_H_
+
+#include "ui/views/view.h"
+
+namespace views {
+class Label;
+}  // namespace views
+
+namespace ash {
+
+class DeskButtonBase;
+class DesksBarView;
+
+// TODO(minch): Build the base class DeskMiniViewBase, and let both the
+// ExpandedStateNewDeskButton and DeskMiniView inherit from it. Then the
+// expanded state new desk button can be treated the same as |mini_views_| in
+// DesksBarView. It then can share the same animation and layout as other mini
+// views.
+// The new desk button view in the expanded desks bar in Bento. It includes the
+// InnerNewDeskButton and a name label below, which has the same style as a
+// DeskMiniVIew. But the name label is not changeable and not focusable.
+class ExpandedStateNewDeskButton : public views::View {
+ public:
+  ExpandedStateNewDeskButton(DesksBarView* bar_view);
+  ExpandedStateNewDeskButton(const ExpandedStateNewDeskButton&) = delete;
+  ExpandedStateNewDeskButton& operator=(const ExpandedStateNewDeskButton&) =
+      delete;
+  ~ExpandedStateNewDeskButton() override = default;
+
+  // views::View:
+  void Layout() override;
+
+  // Updates |new_desk_button_|'s state on current desks state.
+  void UpdateButtonState();
+
+  DeskButtonBase* new_desk_button() { return new_desk_button_; }
+
+ private:
+  DesksBarView* bar_view_;  // Not owned.
+  DeskButtonBase* new_desk_button_;
+  views::Label* label_;
+};
+
+}  // namespace ash
+
+#endif  // ASH_WM_DESKS_EXPANDED_STATE_NEW_DESK_BUTTON_H_

ash/wm/desks/new_desk_button.cc

@@ -23,7 +23,6 @@
 #include "ui/gfx/canvas.h"
 #include "ui/views/animation/ink_drop_impl.h"
 #include "ui/views/background.h"
-#include "ui/views/border.h"
 #include "ui/views/controls/button/label_button_border.h"
 #include "ui/views/controls/highlight_path_generator.h"
 
@@ -159,13 +158,6 @@ SkColor NewDeskButton::GetInkDropBaseColor() const {
       .base_color;
 }
 
-std::unique_ptr<views::LabelButtonBorder> NewDeskButton::CreateDefaultBorder()
-    const {
-  std::unique_ptr<views::LabelButtonBorder> border =
-      std::make_unique<views::LabelButtonBorder>();
-  return border;
-}
-
 void NewDeskButton::OnThemeChanged() {
   LabelButton::OnThemeChanged();
   AshColorProvider::Get()->DecoratePillButton(this, &kDesksNewDeskButtonIcon);

ash/wm/desks/new_desk_button.h

@@ -16,6 +16,8 @@ namespace ash {
 
 class WmHighlightItemBorder;
 
+// TODO(minch): Remove NewDeskButton once Bento feature is fully launched. Since
+// ExpandedStateNewDeskButton will be used instead.
 // A button view that shows up in the top-right corner of the screen when
 // overview mode is on, which is used to create a new virtual desk.
 class ASH_EXPORT NewDeskButton
@@ -49,8 +51,6 @@ class ASH_EXPORT NewDeskButton
   std::unique_ptr<views::InkDropHighlight> CreateInkDropHighlight()
       const override;
   SkColor GetInkDropBaseColor() const override;
-  std::unique_ptr<views::LabelButtonBorder> CreateDefaultBorder()
-      const override;
   void OnThemeChanged() override;
 
   // OverviewHighlightController::OverviewHighlightableView:

ash/wm/desks/zero_state_button.cc

+// Copyright 2021 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/desks/zero_state_button.h"
+
+#include "ash/resources/vector_icons/vector_icons.h"
+#include "ash/strings/grit/ash_strings.h"
+#include "ash/style/ash_color_provider.h"
+#include "ash/wm/desks/desks_bar_view.h"
+#include "ash/wm/desks/desks_controller.h"
+#include "ash/wm/wm_highlight_item_border.h"
+#include "ui/base/l10n/l10n_util.h"
+#include "ui/gfx/canvas.h"
+#include "ui/views/animation/ink_drop_impl.h"
+#include "ui/views/controls/highlight_path_generator.h"
+
+namespace ash {
+
+namespace {
+
+constexpr int kCornerRadius = 8;
+
+constexpr int kZeroStateButtonHeight = 28;
+
+constexpr int kZeroStateDefaultButtonHorizontalPadding = 16;
+
+constexpr int kZeroStateNewDeskButtonWidth = 36;
+
+}  // namespace
+
+// -----------------------------------------------------------------------------
+// DeskButtonBase:
+
+DeskButtonBase::DeskButtonBase(const base::string16& text)
+    : LabelButton(base::BindRepeating(&DeskButtonBase::OnButtonPressed,
+                                      base::Unretained(this)),
+                  text) {
+  SetPaintToLayer();
+  layer()->SetFillsBoundsOpaquely(false);
+  SetHorizontalAlignment(gfx::ALIGN_CENTER);
+
+  SetInkDropMode(InkDropMode::ON);
+  SetHasInkDropActionOnClick(true);
+  SetFocusPainter(nullptr);
+  SetFocusBehavior(views::View::FocusBehavior::ACCESSIBLE_ONLY);
+
+  auto border = std::make_unique<WmHighlightItemBorder>(kCornerRadius);
+  border_ptr_ = border.get();
+  SetBorder(std::move(border));
+  views::InstallRoundRectHighlightPathGenerator(this, GetInsets(),
+                                                kCornerRadius);
+
+  UpdateBorderState();
+}
+
+const char* DeskButtonBase::GetClassName() const {
+  return "DeskButtonBase";
+}
+
+void DeskButtonBase::OnPaintBackground(gfx::Canvas* canvas) {
+  if (highlight_on_hover_) {
+    cc::PaintFlags flags;
+    flags.setAntiAlias(true);
+    flags.setStyle(cc::PaintFlags::kFill_Style);
+    flags.setColor(background_color_);
+    canvas->DrawRoundRect(gfx::RectF(paint_contents_only_ ? GetContentsBounds()
+                                                          : GetLocalBounds()),
+                          kCornerRadius, flags);
+  }
+}
+
+std::unique_ptr<views::InkDrop> DeskButtonBase::CreateInkDrop() {
+  auto ink_drop = CreateDefaultFloodFillInkDropImpl();
+  // Do not show highlight on hover and focus. Since the button will be painted
+  // with a background, see |highlight_on_hover_| for more details.
+  ink_drop->SetShowHighlightOnHover(false);
+  ink_drop->SetShowHighlightOnFocus(false);
+  return std::move(ink_drop);
+}
+
+std::unique_ptr<views::InkDropHighlight>
+DeskButtonBase::CreateInkDropHighlight() const {
+  auto highlight = std::make_unique<views::InkDropHighlight>(
+      gfx::SizeF(size()), GetInkDropBaseColor());
+  highlight->set_visible_opacity(AshColorProvider::Get()
+                                     ->GetRippleAttributes(background_color_)
+                                     .highlight_opacity);
+  return highlight;
+}
+
+SkColor DeskButtonBase::GetInkDropBaseColor() const {
+  return AshColorProvider::Get()
+      ->GetRippleAttributes(background_color_)
+      .base_color;
+}
+
+void DeskButtonBase::OnThemeChanged() {
+  LabelButton::OnThemeChanged();
+  background_color_ = AshColorProvider::Get()->GetControlsLayerColor(
+      AshColorProvider::ControlsLayerType::kControlBackgroundColorInactive);
+  SchedulePaint();
+}
+
+views::View* DeskButtonBase::GetView() {
+  return this;
+}
+
+void DeskButtonBase::MaybeActivateHighlightedView() {
+  OnButtonPressed();
+}
+
+void DeskButtonBase::MaybeCloseHighlightedView() {}
+
+void DeskButtonBase::OnViewHighlighted() {
+  UpdateBorderState();
+}
+
+void DeskButtonBase::OnViewUnhighlighted() {
+  UpdateBorderState();
+}
+
+void DeskButtonBase::UpdateBorderState() {
+  border_ptr_->SetFocused(IsViewHighlighted() &&
+                          DesksController::Get()->CanCreateDesks());
+  SchedulePaint();
+}
+
+// -----------------------------------------------------------------------------
+// ZeroStateDefaultDeskButton:
+
+// TODO(minch): Show the first desk's current name instead of the default name.
+ZeroStateDefaultDeskButton::ZeroStateDefaultDeskButton(DesksBarView* bar_view)
+    : DeskButtonBase(
+          l10n_util::GetStringUTF16(IDS_ASH_DESKS_DESK_1_MINI_VIEW_TITLE)),
+      bar_view_(bar_view) {}
+
+const char* ZeroStateDefaultDeskButton::GetClassName() const {
+  return "ZeroStateDefaultDeskButton";
+}
+
+void ZeroStateDefaultDeskButton::OnThemeChanged() {
+  DeskButtonBase::OnThemeChanged();
+  SetEnabledTextColors(AshColorProvider::Get()->GetContentLayerColor(
+      AshColorProvider::ContentLayerType::kTextColorPrimary));
+}
+
+gfx::Size ZeroStateDefaultDeskButton::CalculatePreferredSize() const {
+  const gfx::Size label_size = label()->GetPreferredSize();
+  return gfx::Size(
+      label_size.width() + 2 * kZeroStateDefaultButtonHorizontalPadding,
+      kZeroStateButtonHeight);
+}
+
+void ZeroStateDefaultDeskButton::OnButtonPressed() {
+  bar_view_->UpdateNewMiniViews(/*initializing_bar_view=*/false,
+                                /*expanding_bar_view=*/true);
+}
+
+// -----------------------------------------------------------------------------
+// ZeroStateNewDeskButton:
+
+ZeroStateNewDeskButton::ZeroStateNewDeskButton()
+    : DeskButtonBase(base::string16()) {
+  highlight_on_hover_ = false;
+}
+
+const char* ZeroStateNewDeskButton::GetClassName() const {
+  return "ZeroStateNewDeskButton";
+}
+
+void ZeroStateNewDeskButton::OnThemeChanged() {
+  DeskButtonBase::OnThemeChanged();
+  AshColorProvider::Get()->DecoratePillButton(this, &kDesksNewDeskButtonIcon);
+}
+
+gfx::Size ZeroStateNewDeskButton::CalculatePreferredSize() const {
+  return gfx::Size(kZeroStateNewDeskButtonWidth, kZeroStateButtonHeight);
+}
+
+void ZeroStateNewDeskButton::OnButtonPressed() {
+  DesksController::Get()->NewDesk(DesksCreationRemovalSource::kButton);
+  highlight_on_hover_ = false;
+}
+
+void ZeroStateNewDeskButton::OnMouseEntered(const ui::MouseEvent& event) {
+  highlight_on_hover_ = true;
+  SchedulePaint();
+}
+
+void ZeroStateNewDeskButton::OnMouseExited(const ui::MouseEvent& event) {
+  highlight_on_hover_ = false;
+  SchedulePaint();
+}
+
+}  // namespace ash

ash/wm/desks/zero_state_button.h

+// Copyright 2021 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_DESKS_ZERO_STATE_BUTTON_H_
+#define ASH_WM_DESKS_ZERO_STATE_BUTTON_H_
+
+#include "ash/ash_export.h"
+#include "ash/wm/overview/overview_highlight_controller.h"
+#include "ui/views/controls/button/label_button.h"
+
+namespace ash {
+
+class DesksBarView;
+class WmHighlightItemBorder;
+
+// The base class of ZeroStateDefaultDeskButton, ZeroStateNewDeskButton and
+// the InnerNewDeskButton of ExpandedStateNewDeskButton.
+class ASH_EXPORT DeskButtonBase
+    : public views::LabelButton,
+      public OverviewHighlightController::OverviewHighlightableView {
+ public:
+  explicit DeskButtonBase(const base::string16& text);
+  ~DeskButtonBase() override = default;
+
+  // LabelButton:
+  const char* GetClassName() const override;
+  void OnPaintBackground(gfx::Canvas* canvas) override;
+  std::unique_ptr<views::InkDrop> CreateInkDrop() override;
+  std::unique_ptr<views::InkDropHighlight> CreateInkDropHighlight()
+      const override;
+  SkColor GetInkDropBaseColor() const override;
+  void OnThemeChanged() override;
+
+  // OverviewHighlightController::OverviewHighlightableView:
+  views::View* GetView() override;
+  void MaybeActivateHighlightedView() override;
+  void MaybeCloseHighlightedView() override;
+  void OnViewHighlighted() override;
+  void OnViewUnhighlighted() override;
+
+  virtual void UpdateButtonState() {}
+
+ protected:
+  virtual void OnButtonPressed() = 0;
+
+  SkColor background_color_;
+
+  // If true, paints the button with the background of |background_color_|. The
+  // button is painted with the background by default, exception like
+  // ZeroStateNewDeskButton only wants to be painted when the mouse hovers.
+  bool highlight_on_hover_ = true;
+
+  // Paints the background within the button's bounds by default. But if true,
+  // paints the contents' bounds of the button only. For example,
+  // InnerNewDeskButton needs to be kept as the same size of the desk preview,
+  // which has a gap between the view's contents and the border.
+  bool paint_contents_only_ = false;
+
+ private:
+  void UpdateBorderState();
+
+  // Owned by this View via `View::border_`. This is just a convenient pointer
+  // to it.
+  WmHighlightItemBorder* border_ptr_;
+};
+
+// A button in zero state bar showing "Desk 1". Zero state is the state of the
+// desks bar when there's only a single desk available, in which case the bar is
+// shown in a minimized state. Clicking the button will switch to the expanded
+// desks bar and focus on the single desk's name view. The expanded bar will
+// include the single desk and the ExpandedStateNewDeskButton.
+class ASH_EXPORT ZeroStateDefaultDeskButton : public DeskButtonBase {
+ public:
+  ZeroStateDefaultDeskButton(DesksBarView* bar_view);
+  ZeroStateDefaultDeskButton(const ZeroStateDefaultDeskButton&) = delete;
+  ZeroStateDefaultDeskButton operator=(const ZeroStateDefaultDeskButton&) =
+      delete;
+  ~ZeroStateDefaultDeskButton() override = default;
+
+  // DeskButtonBase:
+  const char* GetClassName() const override;
+  void OnThemeChanged() override;
+  gfx::Size CalculatePreferredSize() const override;
+  void OnButtonPressed() override;
+
+ private:
+  DesksBarView* bar_view_;
+};
+
+// A button in zero state bar with a plus icon. Zero state is the state of the
+// desks bar when there's only a single desk available, in which case the bar is
+// shown in a minimized state. Clicking the button will create a new desk,
+// switch to the expanded desks bar and focus on the newly-created desks's name
+// view. The expanded bar will include two desks and the
+// ExpandedStateNewDeskButton.
+class ASH_EXPORT ZeroStateNewDeskButton : public DeskButtonBase {
+ public:
+  ZeroStateNewDeskButton();
+  ZeroStateNewDeskButton(const ZeroStateNewDeskButton&) = delete;
+  ZeroStateNewDeskButton operator=(const ZeroStateNewDeskButton&) = delete;
+  ~ZeroStateNewDeskButton() override = default;
+
+  // DeskButtonBase:
+  const char* GetClassName() const override;
+  void OnThemeChanged() override;
+  gfx::Size CalculatePreferredSize() const override;
+  void OnButtonPressed() override;
+
+  // views::Button:
+  void OnMouseEntered(const ui::MouseEvent& event) override;
+  void OnMouseExited(const ui::MouseEvent& event) override;
+};
+
+}  // namespace ash
+
+#endif  // ASH_WM_DESKS_ZERO_STATE_BUTTON_H_

ash/wm/overview/overview_grid.cc

@@ -1331,7 +1331,8 @@ bool OverviewGrid::IsDesksBarViewActive() const {
 
   // The desk bar view is not active if there is only a single desk when
   // overview is started. Once there are more than one desk, it should stay
-  // active even if the 2nd to last desk is deleted.
+  // active even if the 2nd to last desk is deleted in classic desks. Zero state
+  // desks bar in Bento should not be treated as active.
   return DesksController::Get()->desks().size() > 1 ||
          (desks_bar_view_ && !desks_bar_view_->mini_views().empty());
 }

ash/wm/overview/overview_highlight_controller.cc

@@ -6,12 +6,15 @@
 
 #include "ash/magnifier/docked_magnifier_controller_impl.h"
 #include "ash/magnifier/magnification_controller.h"
+#include "ash/public/cpp/ash_features.h"
 #include "ash/shell.h"
 #include "ash/wm/desks/desk_mini_view.h"
 #include "ash/wm/desks/desk_name_view.h"
 #include "ash/wm/desks/desks_bar_view.h"
 #include "ash/wm/desks/desks_util.h"
+#include "ash/wm/desks/expanded_state_new_desk_button.h"
 #include "ash/wm/desks/new_desk_button.h"
+#include "ash/wm/desks/zero_state_button.h"
 #include "ash/wm/overview/overview_grid.h"
 #include "ash/wm/overview/overview_item.h"
 #include "ash/wm/overview/overview_item_view.h"
@@ -205,16 +208,28 @@ OverviewHighlightController::GetTraversableViews() const {
   for (auto& grid : overview_session_->grid_list()) {
     auto* bar_view = grid->desks_bar_view();
     if (bar_view) {
+      const bool is_zero_state = bar_view->IsZeroState();
       // The desk items are always traversable from left to right, even in RTL
       // languages.
+      if (is_zero_state) {
+        traversable_views.push_back(bar_view->zero_state_default_desk_button());
+        traversable_views.push_back(bar_view->zero_state_new_desk_button());
+      } else {
         for (auto* mini_view : bar_view->mini_views()) {
           traversable_views.push_back(mini_view);
           traversable_views.push_back(mini_view->desk_name_view());
         }
+      }
 
-      if (bar_view->new_desk_button()->GetEnabled())
+      if (features::IsBentoEnabled()) {
+        auto* new_desk_button =
+            bar_view->expanded_state_new_desk_button()->new_desk_button();
+        if (!is_zero_state && new_desk_button->GetEnabled())
+          traversable_views.push_back(new_desk_button);
+      } else if (bar_view->new_desk_button()->GetEnabled()) {
         traversable_views.push_back(bar_view->new_desk_button());
       }
+    }
 
     for (auto& item : grid->window_list())
       traversable_views.push_back(item->overview_item_view());

ash/wm/overview/overview_highlight_controller_unittest.cc

@@ -7,12 +7,15 @@
 #include "ash/public/cpp/ash_features.h"
 #include "ash/shell.h"
 #include "ash/test/ash_test_base.h"
+#include "ash/wm/desks/close_desk_button.h"
 #include "ash/wm/desks/desk.h"
 #include "ash/wm/desks/desk_mini_view.h"
 #include "ash/wm/desks/desk_name_view.h"
 #include "ash/wm/desks/desks_bar_view.h"
 #include "ash/wm/desks/desks_test_util.h"
+#include "ash/wm/desks/expanded_state_new_desk_button.h"
 #include "ash/wm/desks/new_desk_button.h"
+#include "ash/wm/desks/zero_state_button.h"
 #include "ash/wm/overview/overview_constants.h"
 #include "ash/wm/overview/overview_controller.h"
 #include "ash/wm/overview/overview_grid.h"
@@ -743,7 +746,9 @@ TEST_F(BentoOverviewHighlightControllerTest,
   ToggleOverview();
   const auto* desk_bar_view =
       GetDesksBarViewForRoot(Shell::GetPrimaryRootWindow());
-  const auto* new_desk_button = desk_bar_view->new_desk_button();
+  ASSERT_FALSE(desk_bar_view->IsZeroState());
+  const auto* new_desk_button =
+      desk_bar_view->expanded_state_new_desk_button()->new_desk_button();
   const auto* desks_controller = DesksController::Get();
 
   auto check_name_view_at_index = [this](const auto* desk_bar_view, int index) {
@@ -776,4 +781,54 @@ TEST_F(BentoOverviewHighlightControllerTest,
             desks_controller->desks().size());
 }
 
+TEST_F(BentoOverviewHighlightControllerTest, ZeroStateOfDesksBar) {
+  ToggleOverview();
+  auto* desks_bar_view = GetDesksBarViewForRoot(Shell::GetPrimaryRootWindow());
+  ASSERT_FALSE(desks_bar_view->IsZeroState());
+  ASSERT_EQ(2u, desks_bar_view->mini_views().size());
+
+  // Remove one desk to enter zero state desks bar.
+  auto* event_generator = GetEventGenerator();
+  auto* mini_view = desks_bar_view->mini_views()[1];
+  event_generator->MoveMouseTo(mini_view->GetBoundsInScreen().CenterPoint());
+  EXPECT_TRUE(mini_view->close_desk_button()->GetVisible());
+  event_generator->MoveMouseTo(
+      mini_view->close_desk_button()->GetBoundsInScreen().CenterPoint());
+  event_generator->ClickLeftButton();
+  EXPECT_TRUE(desks_bar_view->IsZeroState());
+
+  // Both zero state default desk button and zero state new desk button can be
+  // focused in overview mode.
+  SendKey(ui::VKEY_TAB);
+  EXPECT_EQ(desks_bar_view->zero_state_default_desk_button(),
+            GetHighlightedView());
+  SendKey(ui::VKEY_TAB);
+  EXPECT_EQ(desks_bar_view->zero_state_new_desk_button(), GetHighlightedView());
+
+  // Trigger the zero state default desk button will focus on the default desk's
+  // name view.
+  SendKey(ui::VKEY_TAB);
+  EXPECT_EQ(desks_bar_view->zero_state_default_desk_button(),
+            GetHighlightedView());
+  SendKey(ui::VKEY_RETURN);
+  EXPECT_EQ(desks_bar_view->mini_views()[0]->desk_name_view(),
+            GetHighlightedView());
+  ToggleOverview();
+
+  // Trigger the zero state new desk button will focus on the new created desk's
+  // name view.
+  ToggleOverview();
+  EXPECT_TRUE(Shell::Get()->overview_controller()->InOverviewSession());
+  desks_bar_view = GetOverviewSession()
+                       ->GetGridWithRootWindow(Shell::GetPrimaryRootWindow())
+                       ->desks_bar_view();
+  EXPECT_TRUE(desks_bar_view->IsZeroState());
+  SendKey(ui::VKEY_TAB);
+  SendKey(ui::VKEY_TAB);
+  EXPECT_EQ(desks_bar_view->zero_state_new_desk_button(), GetHighlightedView());
+  SendKey(ui::VKEY_RETURN);
+  EXPECT_EQ(desks_bar_view->mini_views()[1]->desk_name_view(),
+            GetHighlightedView());
+}
+
 }  // namespace ash