Refactor platform_services sample (#8949) * Refactor platform_services sample * removed exception

diff --git a/examples/platform_services/android/app/src/androidTest/java/com/example/flutter/ExampleInstrumentedTest.java b/examples/platform_services/android/app/src/androidTest/java/com/example/flutter/ExampleInstrumentedTest.java
index 2fc8eeb..c8dd7a9 100644
--- a/examples/platform_services/android/app/src/androidTest/java/com/example/flutter/ExampleInstrumentedTest.java
+++ b/examples/platform_services/android/app/src/androidTest/java/com/example/flutter/ExampleInstrumentedTest.java

@@ -8,12 +8,8 @@
 import io.flutter.view.FlutterView;
 
 import android.app.Instrumentation;
-import android.support.test.InstrumentationRegistry;
 import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
-import java.util.concurrent.atomic.AtomicInteger;
-import org.json.JSONException;
-import org.json.JSONObject;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
@@ -23,8 +19,8 @@
 @RunWith(AndroidJUnit4.class)
 public class ExampleInstrumentedTest {
     @Rule
-    public ActivityTestRule<ExampleActivity> activityRule =
-        new ActivityTestRule<>(ExampleActivity.class);
+    public ActivityTestRule<MainActivity> activityRule =
+        new ActivityTestRule<>(MainActivity.class);
 
 
     @Test

diff --git a/examples/platform_services/android/app/src/main/AndroidManifest.xml b/examples/platform_services/android/app/src/main/AndroidManifest.xml
index b068bdc..d18170b 100644
--- a/examples/platform_services/android/app/src/main/AndroidManifest.xml
+++ b/examples/platform_services/android/app/src/main/AndroidManifest.xml

@@ -10,7 +10,7 @@
 
     <application android:name="io.flutter.app.FlutterApplication" android:label="@string/app_name" >
         <activity
-            android:name=".ExampleActivity"
+            android:name=".MainActivity"
             android:launchMode="singleTop"
             android:theme="@android:style/Theme.Black.NoTitleBar"
             android:configChanges="orientation|keyboardHidden|keyboard|screenSize|locale|layoutDirection"

diff --git a/examples/platform_services/android/app/src/main/java/com/example/flutter/ExampleActivity.java b/examples/platform_services/android/app/src/main/java/com/example/flutter/MainActivity.java
similarity index 80%
rename from examples/platform_services/android/app/src/main/java/com/example/flutter/ExampleActivity.java
rename to examples/platform_services/android/app/src/main/java/com/example/flutter/MainActivity.java
index 7f2f288..3ce1f03 100644
--- a/examples/platform_services/android/app/src/main/java/com/example/flutter/ExampleActivity.java
+++ b/examples/platform_services/android/app/src/main/java/com/example/flutter/MainActivity.java

@@ -18,7 +18,7 @@
 import io.flutter.plugin.common.FlutterMethodChannel.Response;
 import io.flutter.plugin.common.MethodCall;
 
-public class ExampleActivity extends FlutterActivity {
+public class MainActivity extends FlutterActivity {
   private static final String CHANNEL = "battery";
 
   @Override
@@ -30,15 +30,19 @@
           @Override
           public void onMethodCall(MethodCall call, Response response) {
             if (call.method.equals("getBatteryLevel")) {
-              getBatteryLevel(response);
-            } else {
-              throw new IllegalArgumentException("Unknown method " + call.method);
+              int batteryLevel = getBatteryLevel();
+
+              if (batteryLevel != -1) {
+                response.success(batteryLevel);
+              } else {
+                response.error("UNAVAILABLE", "Battery level not available.", null);
+              }
             }
           }
     });
   }
 
-  private void getBatteryLevel(Response response) {
+  private int getBatteryLevel() {
     int batteryLevel = -1;
     if (VERSION.SDK_INT >= VERSION_CODES.LOLLIPOP) {
       BatteryManager batteryManager = (BatteryManager) getSystemService(BATTERY_SERVICE);
@@ -50,10 +54,6 @@
           intent.getIntExtra(BatteryManager.EXTRA_SCALE, -1);
     }
 
-    if (batteryLevel != -1) {
-      response.success(batteryLevel);
-    } else {
-      response.error("UNAVAILABLE", "Battery level not available.", null);
-    }
+    return batteryLevel;
   }
 }