Refactor hotspot into a full page

- Deprecated WifiAPEnabler, and copied most of its logic into various
  controllers and WifiTetherSettings.
- Added tests

Fix: 37253404
Fix: 36181835

Test: make RunSettingsRoboTests
Change-Id: Iad994d61b694ad7f1113d045a3e7500eeaec178b

src/com/android/settings/wifi/WifiUtils.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2017 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.wifi;
+
+import android.text.TextUtils;
+
+public class WifiUtils {
+
+    private static final int SSID_ASCII_MIN_LENGTH = 1;
+    private static final int SSID_ASCII_MAX_LENGTH = 32;
+    private static final int PASSWORD_MIN_LENGTH = 8;
+    private static final int PASSWORD_MAX_LENGTH = 63;
+
+
+    public static boolean isSSIDTooLong(String ssid) {
+        if (TextUtils.isEmpty(ssid)) {
+            return false;
+        }
+        return ssid.length() > SSID_ASCII_MAX_LENGTH;
+    }
+
+    public static boolean isSSIDTooShort(String ssid) {
+        if (TextUtils.isEmpty(ssid)) {
+            return true;
+        }
+        return ssid.length() < SSID_ASCII_MIN_LENGTH;
+    }
+
+    public static boolean isPasswordValid(String password) {
+        if (TextUtils.isEmpty(password)) {
+            return false;
+        }
+        final int length = password.length();
+        return length >= PASSWORD_MIN_LENGTH && length <= PASSWORD_MAX_LENGTH;
+    }
+}