CrOS Shelf: Introduce a common |ShelfComponent| interface

Bug: 1044306, 1042491, 1040177, 1042911
Change-Id: I37021bfce8f2d6a9b7bcd39df0a3d23eae0b6707
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2028858
Commit-Queue: Manu Cornet <manucornet@chromium.org>
Reviewed-by: Alex Newcomer <newcomer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#736622}

ash/BUILD.gn

@@ -613,6 +613,7 @@ component("ash") {
     "shelf/shelf_button_delegate.h",
     "shelf/shelf_button_pressed_metric_tracker.cc",
     "shelf/shelf_button_pressed_metric_tracker.h",
+    "shelf/shelf_component.h",
     "shelf/shelf_config.cc",
     "shelf/shelf_container_view.cc",
     "shelf/shelf_container_view.h",

ash/shelf/hotseat_widget.cc

@@ -349,6 +349,11 @@ void HotseatWidget::SetTranslucentBackground(
   delegate_view_->SetTranslucentBackground(translucent_background_bounds);
 }
 
+void HotseatWidget::CalculateTargetBounds() {
+  // TODO(manucornet): Move target bounds calculations from the shelf layout
+  // manager.
+}
+
 void HotseatWidget::UpdateLayout(bool animate) {
   const LayoutInputs new_layout_inputs = GetLayoutInputs();
   if (layout_inputs_.has_value() && *layout_inputs_ == new_layout_inputs)

ash/shelf/hotseat_widget.h

@@ -8,6 +8,7 @@
 #include "ash/ash_export.h"
 #include "ash/public/cpp/shelf_config.h"
 #include "ash/public/cpp/shelf_types.h"
+#include "ash/shelf/shelf_component.h"
 #include "base/optional.h"
 #include "ui/views/widget/widget.h"
 
@@ -22,8 +23,9 @@ class Shelf;
 class ShelfView;
 
 // The hotseat widget is part of the shelf and hosts app shortcuts.
-class ASH_EXPORT HotseatWidget : public views::Widget,
-                                 public ShelfConfig::Observer {
+class ASH_EXPORT HotseatWidget : public ShelfComponent,
+                                 public ShelfConfig::Observer,
+                                 public views::Widget {
  public:
   HotseatWidget();
   ~HotseatWidget() override;
@@ -39,7 +41,7 @@ class ASH_EXPORT HotseatWidget : public views::Widget,
   void OnGestureEvent(ui::GestureEvent* event) override;
   bool OnNativeWidgetActivationChanged(bool active) override;
 
-  // ShelfConfig::Observer
+  // ShelfConfig::Observer:
   void OnShelfConfigUpdated() override;
 
   // Whether the overflow menu/bubble is currently being shown.
@@ -65,8 +67,9 @@ class ASH_EXPORT HotseatWidget : public views::Widget,
   // hotseat background.
   void SetTranslucentBackground(const gfx::Rect& background_bounds);
 
-  // Updates this widget's layout according to current conditions.
-  void UpdateLayout(bool animate);
+  // ShelfComponent:
+  void CalculateTargetBounds() override;
+  void UpdateLayout(bool animate) override;
 
   gfx::Size GetTranslucentBackgroundSize() const;
 

ash/shelf/shelf_component.h

+// Copyright 2020 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_SHELF_SHELF_COMPONENT_H_
+#define ASH_SHELF_SHELF_COMPONENT_H_
+
+#include "ash/ash_export.h"
+
+// An interface describing any shelf component such as the navigation widget,
+// the hotseat widget or the status area widget, to make it easier to
+// coordinate animations for all of them.
+class ASH_EXPORT ShelfComponent {
+  // Makes the component calculate its new target bounds given the current
+  // target conditions. It is the component's responsibility to store the
+  // calculated bounds.
+  virtual void CalculateTargetBounds() = 0;
+
+  // Updates the component's layout and bounds to match the most recently
+  // calculated target bounds. The change should be animated if |animate| is
+  // true.
+  virtual void UpdateLayout(bool animate) = 0;
+};
+
+#endif  // ASH_SHELF_SHELF_COMPONENT_H_

ash/shelf/shelf_navigation_widget.cc

@@ -404,6 +404,11 @@ void ShelfNavigationWidget::OnShelfConfigUpdated() {
   UpdateLayout(/*animate=*/true);
 }
 
+void ShelfNavigationWidget::CalculateTargetBounds() {
+  // TODO(manucornet): Move target bounds calculations from the shelf layout
+  // manager.
+}
+
 void ShelfNavigationWidget::UpdateLayout(bool animate) {
   const bool back_button_shown = IsBackButtonShown();
   const bool home_button_shown = IsHomeButtonShown();

ash/shelf/shelf_navigation_widget.h

@@ -8,6 +8,7 @@
 #include "ash/ash_export.h"
 #include "ash/public/cpp/shelf_config.h"
 #include "ash/public/cpp/tablet_mode_observer.h"
+#include "ash/shelf/shelf_component.h"
 #include "ash/shell_observer.h"
 #include "ui/views/accessible_pane_view.h"
 #include "ui/views/widget/widget.h"
@@ -29,10 +30,11 @@ class ShelfView;
 
 // The shelf navigation widget holds the home button and (when in tablet mode)
 // the back button.
-class ASH_EXPORT ShelfNavigationWidget : public views::Widget,
-                                         public TabletModeObserver,
+class ASH_EXPORT ShelfNavigationWidget : public TabletModeObserver,
+                                         public ShelfComponent,
+                                         public ShelfConfig::Observer,
                                          public ShellObserver,
-                                         public ShelfConfig::Observer {
+                                         public views::Widget {
  public:
   class TestApi {
    public:
@@ -89,9 +91,9 @@ class ASH_EXPORT ShelfNavigationWidget : public views::Widget,
   // ShelfConfig::Observer:
   void OnShelfConfigUpdated() override;
 
-  // Updates this widget's layout according to current constraints: tablet
-  // mode and shelf orientation.
-  void UpdateLayout(bool animate);
+  // ShelfComponent:
+  void CalculateTargetBounds() override;
+  void UpdateLayout(bool animate) override;
 
  private:
   class Delegate;

ash/shelf/shelf_widget.cc

@@ -702,6 +702,15 @@ void ShelfWidget::OnBackgroundTypeChanged(ShelfBackgroundType background_type,
   delegate_view_->UpdateOpaqueBackground();
 }
 
+void ShelfWidget::CalculateTargetBounds() {
+  // TODO(manucornet): Move target bounds calculations from the shelf layout
+  // manager.
+}
+
+void ShelfWidget::UpdateLayout(bool animate) {
+  // TODO(manucornet): Refactor layout update logic into this method.
+}
+
 void ShelfWidget::OnSessionStateChanged(session_manager::SessionState state) {
   // Do not show shelf widget:
   // * when views based shelf is disabled

ash/shelf/shelf_widget.h

@@ -14,6 +14,7 @@
 #include "ash/shelf/hotseat_transition_animator.h"
 #include "ash/shelf/hotseat_widget.h"
 #include "ash/shelf/shelf_background_animator.h"
+#include "ash/shelf/shelf_component.h"
 #include "ash/shelf/shelf_layout_manager_observer.h"
 #include "ash/shelf/shelf_observer.h"
 #include "base/macros.h"
@@ -34,11 +35,12 @@ class StatusAreaWidget;
 // The ShelfWidget manages the shelf view (which contains the shelf icons) and
 // the status area widget. There is one ShelfWidget per display. It is created
 // early during RootWindowController initialization.
-class ASH_EXPORT ShelfWidget : public views::Widget,
+class ASH_EXPORT ShelfWidget : public AccessibilityObserver,
+                               public SessionObserver,
+                               public ShelfComponent,
                                public ShelfLayoutManagerObserver,
                                public ShelfObserver,
-                               public SessionObserver,
-                               public AccessibilityObserver {
+                               public views::Widget {
  public:
   explicit ShelfWidget(Shelf* shelf);
   ~ShelfWidget() override;
@@ -106,6 +108,10 @@ class ASH_EXPORT ShelfWidget : public views::Widget,
   void OnGestureEvent(ui::GestureEvent* event) override;
   bool OnNativeWidgetActivationChanged(bool active) override;
 
+  // ShelfComponent:
+  void CalculateTargetBounds() override;
+  void UpdateLayout(bool animate) override;
+
   // ShelfLayoutManagerObserver:
   void WillDeleteShelfLayoutManager() override;
   void OnHotseatStateChanged(HotseatState old_state,