ServiceManager: add getDeclaredInstances

Corresponding to change in IServiceManager API, for finding out what
instances of a VINTF service are installed.

Bug: 168715768
Test: manual
Change-Id: Ic54b0cfd1bd42e45dc66858dbd614db7ba22083f

core/java/android/os/ServiceManager.java

@@ -234,6 +234,21 @@ public final class ServiceManager {
         }
     }
 
+    /**
+     * Returns the list of declared instances for an interface.
+     *
+     * @return true if the service is declared somewhere (eg. VINTF manifest) and
+     * waitForService should always be able to return the service.
+     */
+    public static String[] getDeclaredInstances(@NonNull String iface) {
+        try {
+            return getIServiceManager().getDeclaredInstances(iface);
+        } catch (RemoteException e) {
+            Log.e(TAG, "error in getDeclaredInstances", e);
+            return null;
+        }
+    }
+
     /**
      * Returns the specified service from the service manager.
      *

core/java/android/os/ServiceManagerNative.java

@@ -90,6 +90,10 @@ class ServiceManagerProxy implements IServiceManager {
         return mServiceManager.isDeclared(name);
     }
 
+    public String[] getDeclaredInstances(String iface) throws RemoteException {
+        return mServiceManager.getDeclaredInstances(iface);
+    }
+
     public void registerClientCallback(String name, IBinder service, IClientCallback cb)
             throws RemoteException {
         throw new RemoteException();