Add display settings dashboard to new IA.

- Added a activity-alias pointing to displaySettings as top level
  setting item.
- Refactored all preference logic in DisplaySettings into
  PreferenceControllers. During fragment onAttach it installs all
  controllers, and during onResume it updates preference state. Each
  controller listens to its own preference change event.

Bug: 31800242
Test: RunSettingsRoboTests
Change-Id: Ibc9bf200c5acce7c4ae9292340822afee27a3a28

src/com/android/settings/display/TimeoutPreferenceController.java

@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2016 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.display;
+
+import android.app.admin.DevicePolicyManager;
+import android.content.Context;
+import android.os.UserHandle;
+import android.provider.Settings;
+import android.support.v7.preference.Preference;
+import android.support.v7.preference.PreferenceScreen;
+import android.util.Log;
+
+import com.android.settings.R;
+import com.android.settings.TimeoutListPreference;
+import com.android.settings.core.PreferenceController;
+import com.android.settingslib.RestrictedLockUtils;
+
+import static android.provider.Settings.System.SCREEN_OFF_TIMEOUT;
+
+public class TimeoutPreferenceController extends PreferenceController implements
+        Preference.OnPreferenceChangeListener {
+
+    private static final String TAG = "TimeoutPrefContr";
+
+    /** If there is no setting in the provider, use this. */
+    public static final int FALLBACK_SCREEN_TIMEOUT_VALUE = 30000;
+
+    private static final String KEY_SCREEN_TIMEOUT = "screen_timeout";
+
+    public TimeoutPreferenceController(Context context) {
+        super(context);
+    }
+
+    @Override
+    protected boolean isAvailable() {
+        return true;
+    }
+
+    @Override
+    protected String getPreferenceKey() {
+        return KEY_SCREEN_TIMEOUT;
+    }
+
+    @Override
+    public boolean handlePreferenceTreeClick(Preference preference) {
+        return false;
+    }
+
+    @Override
+    public void updateState(PreferenceScreen screen) {
+        final TimeoutListPreference preference =
+                (TimeoutListPreference) screen.findPreference(KEY_SCREEN_TIMEOUT);
+        if (preference == null) {
+            return;
+        }
+        final long currentTimeout = Settings.System.getLong(mContext.getContentResolver(),
+                SCREEN_OFF_TIMEOUT, FALLBACK_SCREEN_TIMEOUT_VALUE);
+        preference.setValue(String.valueOf(currentTimeout));
+        final DevicePolicyManager dpm = (DevicePolicyManager) mContext.getSystemService(
+                Context.DEVICE_POLICY_SERVICE);
+        if (dpm != null) {
+            final RestrictedLockUtils.EnforcedAdmin admin =
+                    RestrictedLockUtils.checkIfMaximumTimeToLockIsSet(mContext);
+            final long maxTimeout =
+                    dpm.getMaximumTimeToLockForUserAndProfiles(UserHandle.myUserId());
+            preference.removeUnusableTimeouts(maxTimeout, admin);
+        }
+        updateTimeoutPreferenceDescription(preference, currentTimeout);
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        try {
+            int value = Integer.parseInt((String) newValue);
+            Settings.System.putInt(mContext.getContentResolver(), SCREEN_OFF_TIMEOUT, value);
+            updateTimeoutPreferenceDescription((TimeoutListPreference) preference, value);
+        } catch (NumberFormatException e) {
+            Log.e(TAG, "could not persist screen timeout setting", e);
+        }
+        return true;
+    }
+
+    public static CharSequence getTimeoutDescription(
+            long currentTimeout, CharSequence[] entries, CharSequence[] values) {
+        if (currentTimeout < 0 || entries == null || values == null
+                || values.length != entries.length) {
+            return null;
+        }
+
+        for (int i = 0; i < values.length; i++) {
+            long timeout = Long.parseLong(values[i].toString());
+            if (currentTimeout == timeout) {
+                return entries[i];
+            }
+        }
+        return null;
+    }
+
+    private void updateTimeoutPreferenceDescription(TimeoutListPreference preference,
+            long currentTimeout) {
+        final CharSequence[] entries = preference.getEntries();
+        final CharSequence[] values = preference.getEntryValues();
+        final String summary;
+        if (preference.isDisabledByAdmin()) {
+            summary = mContext.getString(com.android.settings.R.string.disabled_by_policy_title);
+        } else {
+            final CharSequence timeoutDescription = getTimeoutDescription(
+                    currentTimeout, entries, values);
+            summary = timeoutDescription == null
+                    ? ""
+                    : mContext.getString(R.string.screen_timeout_summary, timeoutDescription);
+        }
+        preference.setSummary(summary);
+    }
+
+}