MediaRouter: fix no default route

Fix IllegalStateException such that there is no default route.
It happend when invalid route is provided with SystemMeidaRouteProvider
A test is added to check that

Bug: 63630303
Test: Ran MediaRouterInitializationTest
Change-Id: Ib0f12a2c666cb079a8038232090fbf7e90d84921

2 files changed, 71 insertions, 1 deletions

diff --git a/mediarouter/src/androidTest/java/androidx/mediarouter/media/MediaRouterInitializationTest.java b/mediarouter/src/androidTest/java/androidx/mediarouter/media/MediaRouterInitializationTest.java
new file mode 100644
index 00000000000..f3426b59ee7
--- /dev/null
+++ b/mediarouter/src/androidTest/java/androidx/mediarouter/media/MediaRouterInitializationTest.java
@@ -0,0 +1,63 @@
+/*
+ * Copyright 2018 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 androidx.mediarouter.media;
+
+import static androidx.test.InstrumentationRegistry.getContext;
+import static androidx.test.InstrumentationRegistry.getInstrumentation;
+
+import static org.junit.Assert.assertTrue;
+
+import android.content.Context;
+
+import androidx.test.filters.SmallTest;
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/**
+ * Test proper initialization of {@link MediaRouter}.
+ */
+@RunWith(AndroidJUnit4.class)
+public class MediaRouterInitializationTest {
+    /**
+     * This test checks weather MediaRouter is initialized well if an empty route exists
+     */
+    @Test
+    @SmallTest
+    public void testEmptyUserRoute() throws Exception {
+        getInstrumentation().runOnMainSync(new Runnable() {
+            @Override
+            public void run() {
+                final Context context = getContext();
+                android.media.MediaRouter router =
+                        (android.media.MediaRouter) context.getSystemService(
+                                Context.MEDIA_ROUTER_SERVICE);
+
+                // Add empty user route
+                android.media.MediaRouter.RouteCategory category =
+                        router.createRouteCategory("", false);
+                android.media.MediaRouter.UserRouteInfo routeInfo =
+                        router.createUserRoute(category);
+                router.addUserRoute(routeInfo);
+
+                MediaRouter mediaRouter = MediaRouter.getInstance(context);
+                assertTrue(mediaRouter.getDefaultRoute() != null);
+            }
+        });
+    }
+}
diff --git a/mediarouter/src/main/java/androidx/mediarouter/media/MediaRouter.java b/mediarouter/src/main/java/androidx/mediarouter/media/MediaRouter.java
index 007d6ddc3ce..373fefddd3a 100644
--- a/mediarouter/src/main/java/androidx/mediarouter/media/MediaRouter.java
+++ b/mediarouter/src/main/java/androidx/mediarouter/media/MediaRouter.java
@@ -2468,13 +2468,20 @@ public final class MediaRouter {
             // the order of their descriptors.
             int targetIndex = 0;
             boolean selectedRouteDescriptorChanged = false;
-            if (providerDescriptor != null && providerDescriptor.isValid()) {
+            if (providerDescriptor != null && (providerDescriptor.isValid()
+                    || providerDescriptor == mSystemProvider.getDescriptor())) {
                 final List<MediaRouteDescriptor> routeDescriptors = providerDescriptor.getRoutes();
                 // Updating route group's contents requires all member routes' information.
                 // Add the groups to the lists and update them later.
                 List<Pair<RouteInfo, MediaRouteDescriptor>> addedGroups = new ArrayList<>();
                 List<Pair<RouteInfo, MediaRouteDescriptor>> updatedGroups = new ArrayList<>();
                 for (MediaRouteDescriptor routeDescriptor : routeDescriptors) {
+                    // SystemMediaRouteProvider may have invalid routes
+                    if (routeDescriptor == null || !routeDescriptor.isValid()) {
+                        Log.w(TAG, "Ignoring invalid system route descriptor: "
+                                + routeDescriptor);
+                        continue;
+                    }
                     final String id = routeDescriptor.getId();
                     final int sourceIndex = provider.findRouteIndexByDescriptorId(id);
                     boolean isGroup = !(routeDescriptor.getGroupMemberIds().isEmpty());