Add toast error message for no WiFi on wireless debugging.

Show a toast to connect to a WiFi network when the user tries to
enable wireless debugging while not connected to any Wi-Fi network.

Bug: 150139061
Bug: 149843499

Test: make RunSettingsRoboTests ROBOTEST_FILTER=WirelessDebuggingPreferenceControllerTest
Test: make RunSettingsRoboTests ROBOTEST_FILTER=WirelessDebuggingEnablerTest

Change-Id: I389f5fddc874f60e8156ecf6ef2f1c6eddc1d7a5
Exempt-From-Owner-Approval: LGTM
(cherry picked from commit 564f6ba770)

tests/robotests/src/com/android/settings/testutils/shadow/ShadowWirelessDebuggingPreferenceController.java

@@ -0,0 +1,42 @@
+/*
+ * 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.testutils.shadow;
+
+import android.content.Context;
+
+import com.android.settings.development.WirelessDebuggingPreferenceController;
+
+import org.robolectric.annotation.Implementation;
+import org.robolectric.annotation.Implements;
+
+@Implements(WirelessDebuggingPreferenceController.class)
+public class ShadowWirelessDebuggingPreferenceController {
+    private static boolean sIsWifiConnected;
+
+    public static void setIsWifiConnected(boolean isConnected) {
+        sIsWifiConnected = isConnected;
+    }
+
+    public static void reset() {
+        sIsWifiConnected = false;
+    }
+
+    @Implementation
+    protected static boolean isWifiConnected(Context context) {
+        return sIsWifiConnected;
+    }
+}