Disabling elements on the A11y Shortcut setting subpage

Elements on the subpage get disabled if there are no enabled shortcut targets for the relevant type.
In the case of A11y button, the items on its fragment become unsearchable when the setting is disabled.

Test: Manually verify conditions described above & in bug
Bug: 349180207
Flag: com.android.settings.accessibility.fix_a11y_settings_search
Change-Id: Id39e2eda6c9d1de4cdbfcbc22b8a1f443e2822d9

src/com/android/settings/accessibility/HardwareShortcutFromLockscreenPreferenceController.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.android.settings.accessibility;
+
+import static com.android.internal.accessibility.common.ShortcutConstants.UserShortcutType.HARDWARE;
+import static com.android.settings.accessibility.AccessibilityUtil.State.OFF;
+import static com.android.settings.accessibility.AccessibilityUtil.State.ON;
+
+import android.content.ContentResolver;
+import android.content.Context;
+import android.os.UserHandle;
+import android.provider.Settings;
+import android.view.accessibility.AccessibilityManager;
+
+import androidx.annotation.NonNull;
+import androidx.preference.Preference;
+
+import com.android.settings.R;
+import com.android.settings.core.TogglePreferenceController;
+
+/**
+ * Setting to allow the hardware shortcut to turn on from the lock screen
+ */
+public class HardwareShortcutFromLockscreenPreferenceController
+        extends TogglePreferenceController {
+    public HardwareShortcutFromLockscreenPreferenceController(
+            Context context, String preferenceKey) {
+        super(context, preferenceKey);
+    }
+
+    @Override
+    public boolean isChecked() {
+        final ContentResolver cr = mContext.getContentResolver();
+        // The shortcut is enabled by default on the lock screen as long as the user has
+        // enabled the shortcut with the warning dialog
+        final int dialogShown = Settings.Secure.getInt(
+                cr, Settings.Secure.ACCESSIBILITY_SHORTCUT_DIALOG_SHOWN, OFF);
+        final boolean enabledFromLockScreen = Settings.Secure.getInt(
+                cr, Settings.Secure.ACCESSIBILITY_SHORTCUT_ON_LOCK_SCREEN, dialogShown) == ON;
+        return enabledFromLockScreen;
+    }
+
+    @Override
+    public boolean setChecked(boolean isChecked) {
+        return Settings.Secure.putIntForUser(mContext.getContentResolver(),
+                Settings.Secure.ACCESSIBILITY_SHORTCUT_ON_LOCK_SCREEN, isChecked ? ON : OFF,
+                UserHandle.USER_CURRENT);
+    }
+
+    @Override
+    public int getAvailabilityStatus() {
+        if (!com.android.settings.accessibility.Flags.fixA11ySettingsSearch()) {
+            return AVAILABLE;
+        } else {
+            if (mContext.getSystemService(AccessibilityManager.class)
+                    .getAccessibilityShortcutTargets(HARDWARE).isEmpty()) {
+                return DISABLED_DEPENDENT_SETTING;
+            } else {
+                return AVAILABLE;
+            }
+        }
+    }
+
+    @Override
+    public void updateState(@NonNull Preference preference) {
+        super.updateState(preference);
+        refreshSummary(preference);
+    }
+
+    @Override
+    public @NonNull CharSequence getSummary() {
+        if (getAvailabilityStatus() == AVAILABLE) {
+            return mContext.getString(R.string.accessibility_shortcut_description);
+        } else {
+            return mContext.getString(
+                    R.string.accessibility_shortcut_unassigned_setting_unavailable_summary,
+                    AccessibilityUtil.getShortcutSummaryList(mContext, HARDWARE));
+        }
+    }
+
+    @Override
+    public int getSliceHighlightMenuRes() {
+        return R.string.menu_key_accessibility;
+    }
+}