Display "see all" option when bluetooth is off

- This CL before, Bluetooth settings will hide the "see all"
  option when bluetooth is off. For the UX improvement, this
  CL will show the "see all" button when bluetooth is off. And
  turn on the BT when user press "see all" button to let user to
  quick pair their disconnected devices.
- Update and add test case

Bug: 147150367
Test: make -j42 RunSettingsRoboTests
Change-Id: I7a1451a36a31253b6be2203341bea4e59fed7c2b

src/com/android/settings/connecteddevice/PreviouslyConnectedDevicePreferenceController.java

@@ -15,7 +15,11 @@
  */
 package com.android.settings.connecteddevice;
 
+import android.bluetooth.BluetoothAdapter;
+import android.content.BroadcastReceiver;
 import android.content.Context;
+import android.content.Intent;
+import android.content.IntentFilter;
 import android.content.pm.PackageManager;
 
 import androidx.annotation.VisibleForTesting;
@@ -23,6 +27,7 @@ import androidx.preference.Preference;
 import androidx.preference.PreferenceGroup;
 import androidx.preference.PreferenceScreen;
 
+import com.android.settings.R;
 import com.android.settings.bluetooth.BluetoothDeviceUpdater;
 import com.android.settings.bluetooth.SavedBluetoothDeviceUpdater;
 import com.android.settings.connecteddevice.dock.DockUpdater;
@@ -37,17 +42,34 @@ public class PreviouslyConnectedDevicePreferenceController extends BasePreferenc
         implements LifecycleObserver, OnStart, OnStop, DevicePreferenceCallback {
 
     private static final int MAX_DEVICE_NUM = 3;
+    private static final String KEY_SEE_ALL = "previously_connected_devices_see_all";
 
     private PreferenceGroup mPreferenceGroup;
     private BluetoothDeviceUpdater mBluetoothDeviceUpdater;
     private DockUpdater mSavedDockUpdater;
     private int mPreferenceSize;
+    private BluetoothAdapter mBluetoothAdapter;
+
+    @VisibleForTesting
+    Preference mSeeAllPreference;
+    @VisibleForTesting
+    IntentFilter mIntentFilter;
+
+    @VisibleForTesting
+    BroadcastReceiver mReceiver = new BroadcastReceiver() {
+        @Override
+        public void onReceive(Context context, Intent intent) {
+            updatePreferenceVisibility();
+        }
+    };
 
     public PreviouslyConnectedDevicePreferenceController(Context context, String preferenceKey) {
         super(context, preferenceKey);
 
         mSavedDockUpdater = FeatureFactory.getFactory(
                 context).getDockUpdaterFeatureProvider().getSavedDockUpdater(context, this);
+        mIntentFilter = new IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED);
+        mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
     }
 
     @Override
@@ -62,7 +84,8 @@ public class PreviouslyConnectedDevicePreferenceController extends BasePreferenc
     public void displayPreference(PreferenceScreen screen) {
         super.displayPreference(screen);
         mPreferenceGroup = screen.findPreference(getPreferenceKey());
-        mPreferenceGroup.setVisible(false);
+        mSeeAllPreference = mPreferenceGroup.findPreference(KEY_SEE_ALL);
+        updatePreferenceVisibility();
 
         if (isAvailable()) {
             final Context context = screen.getContext();
@@ -75,12 +98,14 @@ public class PreviouslyConnectedDevicePreferenceController extends BasePreferenc
     public void onStart() {
         mBluetoothDeviceUpdater.registerCallback();
         mSavedDockUpdater.registerCallback();
+        mContext.registerReceiver(mReceiver, mIntentFilter);
     }
 
     @Override
     public void onStop() {
         mBluetoothDeviceUpdater.unregisterCallback();
         mSavedDockUpdater.unregisterCallback();
+        mContext.unregisterReceiver(mReceiver);
     }
 
     public void init(DashboardFragment fragment) {
@@ -94,14 +119,14 @@ public class PreviouslyConnectedDevicePreferenceController extends BasePreferenc
         if (mPreferenceSize <= MAX_DEVICE_NUM) {
             mPreferenceGroup.addPreference(preference);
         }
-        updatePreferenceVisiblity();
+        updatePreferenceVisibility();
     }
 
     @Override
     public void onDeviceRemoved(Preference preference) {
         mPreferenceSize--;
         mPreferenceGroup.removePreference(preference);
-        updatePreferenceVisiblity();
+        updatePreferenceVisibility();
     }
 
     @VisibleForTesting
@@ -120,7 +145,12 @@ public class PreviouslyConnectedDevicePreferenceController extends BasePreferenc
     }
 
     @VisibleForTesting
-    void updatePreferenceVisiblity() {
-        mPreferenceGroup.setVisible(mPreferenceSize > 0);
+    void updatePreferenceVisibility() {
+        if (mBluetoothAdapter != null && mBluetoothAdapter.isEnabled()) {
+            mSeeAllPreference.setSummary("");
+        } else {
+            mSeeAllPreference.setSummary(
+                    mContext.getString(R.string.connected_device_see_all_summary));
+        }
     }
 }