Update shelf control buttons visibility for accessibility

Makes shelf control buttons (home, back, overview) show up regardless of
kHideShelfControlsInTabletMode if they're needed for accessibiltiy
reasons - i.e. if one of the accessibility features is enabled:
*   spoken feedback
*   autoclick
*   switch access

BUG=1012814

Change-Id: I83925d201e8551a694a444a8cbc1f69d71892a7a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2024034
Commit-Queue: Toni Baržić <tbarzic@chromium.org>
Reviewed-by: Manu Cornet <manucornet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735992}

ash/public/cpp/shelf_config.h

@@ -181,6 +181,8 @@ class ASH_EXPORT ShelfConfig : public TabletModeObserver,
  private:
   friend class ShelfConfigTest;
 
+  class ShelfAccessibilityObserver;
+
   // Called whenever something has changed in the shelf configuration. Notifies
   // all observers.
   void OnShelfConfigUpdated();
@@ -195,6 +197,9 @@ class ASH_EXPORT ShelfConfig : public TabletModeObserver,
   //                         calculated as if is_in_app() returns false.
   int GetShelfSize(bool ignore_in_app_state) const;
 
+  // Updates shelf config - called when the accessibility state changes.
+  void UpdateConfigForAccessibilityState();
+
   // Whether shelf is currently standard or dense.
   bool is_dense_;
 
@@ -276,6 +281,10 @@ class ASH_EXPORT ShelfConfig : public TabletModeObserver,
   // tablet mode.
   const int app_icon_end_padding_;
 
+  // Object responsible for observing accessibility settings relevant to shelf
+  // config.
+  std::unique_ptr<ShelfAccessibilityObserver> accessibility_observer_;
+
   base::ObserverList<Observer> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfConfig);

ash/shelf/back_button_unittest.cc

@@ -7,8 +7,10 @@
 #include <memory>
 
 #include "ash/accelerators/accelerator_controller_impl.h"
+#include "ash/accessibility/accessibility_controller_impl.h"
 #include "ash/app_list/test/app_list_test_helper.h"
 #include "ash/app_list/views/app_list_view.h"
+#include "ash/public/cpp/ash_features.h"
 #include "ash/shelf/shelf.h"
 #include "ash/shelf/shelf_navigation_widget.h"
 #include "ash/shelf/shelf_view.h"
@@ -26,6 +28,8 @@
 
 namespace ash {
 
+namespace {
+
 class BackButtonTest : public AshTestBase,
                        public testing::WithParamInterface<bool> {
  public:
@@ -76,6 +80,48 @@ class BackButtonTest : public AshTestBase,
   DISALLOW_COPY_AND_ASSIGN(BackButtonTest);
 };
 
+enum class TestAccessibilityFeature {
+  kSpokenFeedback,
+  kAutoclick,
+  kSwitchAccess
+};
+
+// Tests back button visibility with number of accessibility setting enabled,
+// with kHideControlsInTabletModeFeature.
+class BackButtonVisibilityWithAccessibilityFeaturesTest
+    : public AshTestBase,
+      public ::testing::WithParamInterface<TestAccessibilityFeature> {
+ public:
+  BackButtonVisibilityWithAccessibilityFeaturesTest() {
+    scoped_feature_list_.InitWithFeatures(
+        {chromeos::features::kShelfHotseat,
+         features::kHideShelfControlsInTabletMode},
+        {});
+  }
+  ~BackButtonVisibilityWithAccessibilityFeaturesTest() override = default;
+
+  void SetTestA11yFeatureEnabled(bool enabled) {
+    switch (GetParam()) {
+      case TestAccessibilityFeature::kSpokenFeedback:
+        Shell::Get()->accessibility_controller()->SetSpokenFeedbackEnabled(
+            enabled, A11Y_NOTIFICATION_NONE);
+        break;
+      case TestAccessibilityFeature::kAutoclick:
+        Shell::Get()->accessibility_controller()->SetAutoclickEnabled(enabled);
+        break;
+      case TestAccessibilityFeature::kSwitchAccess:
+        Shell::Get()->accessibility_controller()->SetSwitchAccessEnabled(
+            enabled);
+        break;
+    }
+  }
+
+ private:
+  base::test::ScopedFeatureList scoped_feature_list_;
+};
+
+}  // namespace
+
 // The parameter indicates whether the kShelfHotseat feature is enabled.
 INSTANTIATE_TEST_SUITE_P(All, BackButtonTest, testing::Bool());
 
@@ -203,4 +249,49 @@ TEST_P(BackButtonTest, NoContextMenuOnBackButton) {
   EXPECT_FALSE(test_api_->CloseMenu());
 }
 
+INSTANTIATE_TEST_SUITE_P(
+    All,
+    BackButtonVisibilityWithAccessibilityFeaturesTest,
+    ::testing::Values(TestAccessibilityFeature::kSpokenFeedback,
+                      TestAccessibilityFeature::kAutoclick,
+                      TestAccessibilityFeature::kSwitchAccess));
+
+TEST_P(BackButtonVisibilityWithAccessibilityFeaturesTest,
+       TabletModeSwitchWithA11yFeatureEnabled) {
+  std::unique_ptr<views::Widget> widget = CreateTestWidget();
+
+  SetTestA11yFeatureEnabled(true /*enabled*/);
+
+  ShelfNavigationWidget::TestApi test_api(
+      GetPrimaryShelf()->shelf_widget()->navigation_widget());
+  // Back button is not shown in clamshell.
+  EXPECT_FALSE(test_api.IsBackButtonVisible());
+
+  // Switch to tablet mode, and verify the back button is now visible.
+  Shell::Get()->tablet_mode_controller()->SetEnabledForTest(true);
+  EXPECT_TRUE(test_api.IsBackButtonVisible());
+
+  // The button should be hidden if the feature gets disabled.
+  SetTestA11yFeatureEnabled(false /*enabled*/);
+  EXPECT_FALSE(test_api.IsBackButtonVisible());
+}
+
+TEST_P(BackButtonVisibilityWithAccessibilityFeaturesTest,
+       FeatureEnabledWhileInTabletMode) {
+  std::unique_ptr<views::Widget> widget = CreateTestWidget();
+
+  ShelfNavigationWidget::TestApi test_api(
+      GetPrimaryShelf()->shelf_widget()->navigation_widget());
+  // Back button is not shown in clamshell.
+  EXPECT_FALSE(test_api.IsBackButtonVisible());
+
+  // Switch to tablet mode, and verify the back button is still hidden.
+  Shell::Get()->tablet_mode_controller()->SetEnabledForTest(true);
+  EXPECT_FALSE(test_api.IsBackButtonVisible());
+
+  // The button should be shown if the feature gets enabled.
+  SetTestA11yFeatureEnabled(true /*enabled*/);
+  EXPECT_TRUE(test_api.IsBackButtonVisible());
+}
+
 }  // namespace ash

ash/shelf/home_button_unittest.cc

@@ -7,6 +7,7 @@
 #include <memory>
 #include <string>
 
+#include "ash/accessibility/accessibility_controller_impl.h"
 #include "ash/app_list/test/app_list_test_helper.h"
 #include "ash/app_list/views/app_list_view.h"
 #include "ash/assistant/assistant_controller.h"
@@ -41,8 +42,6 @@ ui::GestureEvent CreateGestureEvent(ui::GestureEventDetails details) {
   return ui::GestureEvent(0, 0, ui::EF_NONE, base::TimeTicks(), details);
 }
 
-}  // namespace
-
 class HomeButtonTest
     : public AshTestBase,
       public testing::WithParamInterface<std::tuple<bool, bool>> {
@@ -117,6 +116,48 @@ class HomeButtonTest
   DISALLOW_COPY_AND_ASSIGN(HomeButtonTest);
 };
 
+enum class TestAccessibilityFeature {
+  kSpokenFeedback,
+  kAutoclick,
+  kSwitchAccess
+};
+
+// Tests home button visibility with number of accessibility setting enabled,
+// with kHideControlsInTabletModeFeature.
+class HomeButtonVisibilityWithAccessibilityFeaturesTest
+    : public AshTestBase,
+      public ::testing::WithParamInterface<TestAccessibilityFeature> {
+ public:
+  HomeButtonVisibilityWithAccessibilityFeaturesTest() {
+    scoped_feature_list_.InitWithFeatures(
+        {chromeos::features::kShelfHotseat,
+         features::kHideShelfControlsInTabletMode},
+        {});
+  }
+  ~HomeButtonVisibilityWithAccessibilityFeaturesTest() override = default;
+
+  void SetTestA11yFeatureEnabled(bool enabled) {
+    switch (GetParam()) {
+      case TestAccessibilityFeature::kSpokenFeedback:
+        Shell::Get()->accessibility_controller()->SetSpokenFeedbackEnabled(
+            enabled, A11Y_NOTIFICATION_NONE);
+        break;
+      case TestAccessibilityFeature::kAutoclick:
+        Shell::Get()->accessibility_controller()->SetAutoclickEnabled(enabled);
+        break;
+      case TestAccessibilityFeature::kSwitchAccess:
+        Shell::Get()->accessibility_controller()->SetSwitchAccessEnabled(
+            enabled);
+        break;
+    }
+  }
+
+ private:
+  base::test::ScopedFeatureList scoped_feature_list_;
+};
+
+}  // namespace
+
 // The parameters indicate whether the kShelfHotseat and
 // kHideShelfControlsInTabletMode features are enabled.
 INSTANTIATE_TEST_SUITE_P(All,
@@ -531,4 +572,43 @@ TEST_P(HomeButtonTest, ClickOnCornerPixel) {
   GetAppListTestHelper()->CheckVisibility(true);
 }
 
+INSTANTIATE_TEST_SUITE_P(
+    All,
+    HomeButtonVisibilityWithAccessibilityFeaturesTest,
+    ::testing::Values(TestAccessibilityFeature::kSpokenFeedback,
+                      TestAccessibilityFeature::kAutoclick,
+                      TestAccessibilityFeature::kSwitchAccess));
+
+TEST_P(HomeButtonVisibilityWithAccessibilityFeaturesTest,
+       TabletModeSwitchWithA11yFeatureEnabled) {
+  SetTestA11yFeatureEnabled(true /*enabled*/);
+
+  ShelfNavigationWidget::TestApi test_api(
+      GetPrimaryShelf()->shelf_widget()->navigation_widget());
+  EXPECT_TRUE(test_api.IsHomeButtonVisible());
+
+  // Switch to tablet mode, and verify the home button is still visible.
+  Shell::Get()->tablet_mode_controller()->SetEnabledForTest(true);
+  EXPECT_TRUE(test_api.IsHomeButtonVisible());
+
+  // The button should be hidden if the feature gets disabled.
+  SetTestA11yFeatureEnabled(false /*enabled*/);
+  EXPECT_FALSE(test_api.IsHomeButtonVisible());
+}
+
+TEST_P(HomeButtonVisibilityWithAccessibilityFeaturesTest,
+       FeatureEnabledWhileInTabletMode) {
+  ShelfNavigationWidget::TestApi test_api(
+      GetPrimaryShelf()->shelf_widget()->navigation_widget());
+  EXPECT_TRUE(test_api.IsHomeButtonVisible());
+
+  // Switch to tablet mode, and verify the home button is hidden.
+  Shell::Get()->tablet_mode_controller()->SetEnabledForTest(true);
+  EXPECT_FALSE(test_api.IsHomeButtonVisible());
+
+  // The button should be shown if the feature gets enabled.
+  SetTestA11yFeatureEnabled(true /*enabled*/);
+  EXPECT_TRUE(test_api.IsHomeButtonVisible());
+}
+
 }  // namespace ash

ash/shelf/shelf_config.cc

@@ -4,6 +4,8 @@
 
 #include "ash/public/cpp/shelf_config.h"
 
+#include "ash/accessibility/accessibility_controller_impl.h"
+#include "ash/accessibility/accessibility_observer.h"
 #include "ash/app_list/app_list_controller_impl.h"
 #include "ash/public/cpp/ash_features.h"
 #include "ash/session/session_controller_impl.h"
@@ -11,6 +13,7 @@
 #include "ash/style/ash_color_provider.h"
 #include "ash/wallpaper/wallpaper_controller_impl.h"
 #include "ash/wm/tablet_mode/tablet_mode_controller.h"
+#include "base/scoped_observer.h"
 #include "chromeos/constants/chromeos_switches.h"
 #include "ui/gfx/color_analysis.h"
 #include "ui/gfx/color_palette.h"
@@ -30,8 +33,46 @@ bool IsTabletMode() {
          Shell::Get()->tablet_mode_controller()->InTabletMode();
 }
 
+// Whether the the shelf control buttons must be shown for accessibility
+// reasons.
+bool ShelfControlsForcedShownForAccessibility() {
+  AccessibilityControllerImpl* accessibility_controller =
+      Shell::Get()->accessibility_controller();
+  return accessibility_controller->spoken_feedback_enabled() ||
+         accessibility_controller->autoclick_enabled() ||
+         accessibility_controller->switch_access_enabled();
+}
+
 }  // namespace
 
+class ShelfConfig::ShelfAccessibilityObserver : public AccessibilityObserver {
+ public:
+  ShelfAccessibilityObserver(
+      const base::RepeatingClosure& accessibility_state_changed_callback)
+      : accessibility_state_changed_callback_(
+            accessibility_state_changed_callback) {
+    observer_.Add(Shell::Get()->accessibility_controller());
+  }
+
+  ShelfAccessibilityObserver(const ShelfAccessibilityObserver& other) = delete;
+  ShelfAccessibilityObserver& operator=(
+      const ShelfAccessibilityObserver& other) = delete;
+
+  ~ShelfAccessibilityObserver() override = default;
+
+  // AccessibilityObserver:
+  void OnAccessibilityStatusChanged() override {
+    accessibility_state_changed_callback_.Run();
+  }
+  void OnAccessibilityControllerShutdown() override { observer_.RemoveAll(); }
+
+ private:
+  base::RepeatingClosure accessibility_state_changed_callback_;
+
+  ScopedObserver<AccessibilityControllerImpl, AccessibilityObserver> observer_{
+      this};
+};
+
 ShelfConfig::ShelfConfig()
     : is_dense_(false),
       shelf_controls_shown_(true),
@@ -63,6 +104,9 @@ ShelfConfig::ShelfConfig()
       mousewheel_scroll_offset_threshold_(20),
       in_app_control_button_height_inset_(4),
       app_icon_end_padding_(4) {
+  accessibility_observer_ = std::make_unique<ShelfAccessibilityObserver>(
+      base::BindRepeating(&ShelfConfig::UpdateConfigForAccessibilityState,
+                          base::Unretained(this)));
   UpdateConfig(is_app_list_visible_);
 }
 
@@ -228,7 +272,8 @@ void ShelfConfig::UpdateConfig(bool app_list_visible) {
   // TODO(http::crbug.com/1008956): Add a user preference that would allow the
   // user or a policy to override this behavior.
   const bool new_shelf_controls_shown =
-      !(in_tablet_mode && features::IsHideShelfControlsInTabletModeEnabled());
+      !(in_tablet_mode && features::IsHideShelfControlsInTabletModeEnabled()) ||
+      ShelfControlsForcedShownForAccessibility();
 
   if (new_is_dense == is_dense_ &&
       shelf_controls_shown_ == new_shelf_controls_shown &&
@@ -342,6 +387,10 @@ int ShelfConfig::GetAppIconEndPadding() const {
              : 0;
 }
 
+void ShelfConfig::UpdateConfigForAccessibilityState() {
+  UpdateConfig(is_app_list_visible_);
+}
+
 void ShelfConfig::OnShelfConfigUpdated() {
   for (auto& observer : observers_)
     observer.OnShelfConfigUpdated();