Define getLooper() method

The default implementation uses the main looper to handle service
operations. This is generally okay until we have to make network
calls to retrieve resolution data.

Bug: 25119046
Test: manual
Change-Id: I22b0f279e6c1fde21f207578d2930ab4858bbc78

api/system-current.txt

@@ -4554,6 +4554,7 @@ package android.app {
   public abstract class EphemeralResolverService extends android.app.Service {
     ctor public EphemeralResolverService();
     method public final void attachBaseContext(android.content.Context);
+    method public android.os.Looper getLooper();
     method public final android.os.IBinder onBind(android.content.Intent);
     method public abstract deprecated java.util.List<android.content.pm.EphemeralResolveInfo> onEphemeralResolveInfoList(int[], int);
     method public android.content.pm.EphemeralResolveInfo onGetEphemeralIntentFilter(java.lang.String);

core/java/android/app/EphemeralResolverService.java

@@ -74,10 +74,17 @@ public abstract class EphemeralResolverService extends Service {
         throw new IllegalStateException("Must define");
     }
 
+    /**
+     * Returns a {@link Looper} to perform service operations on.
+     */
+    public Looper getLooper() {
+        return getBaseContext().getMainLooper();
+    }
+
     @Override
     public final void attachBaseContext(Context base) {
         super.attachBaseContext(base);
-        mHandler = new ServiceHandler(base.getMainLooper());
+        mHandler = new ServiceHandler(getLooper());
     }
 
     @Override