When running in AOT modes create a flutter_assets directory that can …

…be used as the bundle path (flutter#9306)

The engine RunBundleAndSnapshotFromLibrary API expects a bundle path directory
containing the application's assets.  If the Android embedding is using
AOT ELF library packaging and does not need to extract assets, then create an
empty directory at the bundle path.

Fixes flutter#34287

shell/platform/android/io/flutter/view/FlutterMain.java

@@ -143,7 +143,9 @@ public static void ensureInitializationComplete(@NonNull Context applicationCont
             return;
         }
         try {
-            sResourceExtractor.waitForCompletion();
+            if (sResourceExtractor != null) {
+                sResourceExtractor.waitForCompletion();
+            }
 
             List<String> shellArgs = new ArrayList<>();
             shellArgs.add("--icu-symbol-prefix=_binary_icudtl_dat");
@@ -258,23 +260,28 @@ private static void initResources(@NonNull Context applicationContext) {
         new ResourceCleaner(applicationContext).start();
 
         final String dataDirPath = PathUtils.getDataDirectory(applicationContext);
-        final String packageName = applicationContext.getPackageName();
-        final PackageManager packageManager = applicationContext.getPackageManager();
-        final AssetManager assetManager = applicationContext.getResources().getAssets();
-        sResourceExtractor = new ResourceExtractor(dataDirPath, packageName, packageManager, assetManager);
-
-        // In debug/JIT mode these assets will be written to disk and then
-        // mapped into memory so they can be provided to the Dart VM.
-        // AOT modes obtain compiled Dart assets from a ELF library that does
-        // not need to be extracted out of the APK.
+
         if (BuildConfig.DEBUG) {
-          sResourceExtractor
-              .addResource(fromFlutterAssets(sVmSnapshotData))
-              .addResource(fromFlutterAssets(sIsolateSnapshotData))
-              .addResource(fromFlutterAssets(DEFAULT_KERNEL_BLOB));
+            final String packageName = applicationContext.getPackageName();
+            final PackageManager packageManager = applicationContext.getPackageManager();
+            final AssetManager assetManager = applicationContext.getResources().getAssets();
+            sResourceExtractor = new ResourceExtractor(dataDirPath, packageName, packageManager, assetManager);
+
+            // In debug/JIT mode these assets will be written to disk and then
+            // mapped into memory so they can be provided to the Dart VM.
+            sResourceExtractor
+                .addResource(fromFlutterAssets(sVmSnapshotData))
+                .addResource(fromFlutterAssets(sIsolateSnapshotData))
+                .addResource(fromFlutterAssets(DEFAULT_KERNEL_BLOB));
+
+            sResourceExtractor.start();
+        } else {
+            // AOT modes obtain compiled Dart assets from a ELF library that does
+            // not need to be extracted out of the APK.
+            // Create an empty directory that can be passed as the bundle path
+            // in the engine RunBundle API.
+            new File(dataDirPath, sFlutterAssetsDir).mkdirs();
         }
-
-        sResourceExtractor.start();
     }
 
     @Nullable