Fix some potential Uri nullness violations.

PiperOrigin-RevId: 223476569

library/core/src/main/java/com/google/android/exoplayer2/upstream/DefaultDataSource.java

@@ -228,7 +228,8 @@ public final class DefaultDataSource implements DataSource {
     // Choose the correct source for the scheme.
     String scheme = dataSpec.uri.getScheme();
     if (Util.isLocalFileUri(dataSpec.uri)) {
-      if (dataSpec.uri.getPath().startsWith("/android_asset/")) {
+      String uriPath = dataSpec.uri.getPath();
+      if (uriPath != null && uriPath.startsWith("/android_asset/")) {
         dataSource = getAssetDataSource();
       } else {
         dataSource = getFileDataSource();

library/core/src/main/java/com/google/android/exoplayer2/util/Util.java

@@ -204,7 +204,8 @@ public final class Util {
     }
     for (Uri uri : uris) {
       if ("http".equals(uri.getScheme())
-          && !NetworkSecurityPolicy.getInstance().isCleartextTrafficPermitted(uri.getHost())) {
+          && !NetworkSecurityPolicy.getInstance()
+              .isCleartextTrafficPermitted(Assertions.checkNotNull(uri.getHost()))) {
         // The security policy prevents cleartext traffic.
         return false;
       }

library/smoothstreaming/src/main/java/com/google/android/exoplayer2/source/smoothstreaming/manifest/SsUtil.java

@@ -23,7 +23,9 @@ public final class SsUtil {
 
   /** Returns a fixed SmoothStreaming client manifest {@link Uri}. */
   public static Uri fixManifestUri(Uri manifestUri) {
-    if (Util.toLowerInvariant(manifestUri.getLastPathSegment()).matches("manifest(\\(.+\\))?")) {
+    String lastPathSegment = manifestUri.getLastPathSegment();
+    if (lastPathSegment != null
+        && Util.toLowerInvariant(lastPathSegment).matches("manifest(\\(.+\\))?")) {
       return manifestUri;
     }
     return Uri.withAppendedPath(manifestUri, "Manifest");