Request notification permission when starting session demo app

#minor-release

PiperOrigin-RevId: 572556101

demos/session/src/main/java/androidx/media3/demo/session/MainActivity.kt

@@ -15,8 +15,11 @@
  */
 package androidx.media3.demo.session
 
+import android.Manifest
 import android.content.ComponentName
 import android.content.Context
+import android.content.pm.PackageManager
+import android.os.Build
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.MenuItem
@@ -25,6 +28,7 @@ import android.view.ViewGroup
 import android.widget.ArrayAdapter
 import android.widget.ListView
 import android.widget.TextView
+import android.widget.Toast
 import androidx.activity.OnBackPressedCallback
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.content.ContextCompat
@@ -81,6 +85,14 @@ class MainActivity : AppCompatActivity() {
         }
       }
     )
+
+    if (
+      Build.VERSION.SDK_INT >= 33 &&
+        checkSelfPermission(Manifest.permission.POST_NOTIFICATIONS) !=
+          PackageManager.PERMISSION_GRANTED
+    ) {
+      requestPermissions(arrayOf(Manifest.permission.POST_NOTIFICATIONS), /* requestCode= */ 0)
+    }
   }
 
   override fun onOptionsItemSelected(item: MenuItem): Boolean {
@@ -101,6 +113,23 @@ class MainActivity : AppCompatActivity() {
     super.onStop()
   }
 
+  override fun onRequestPermissionsResult(
+    requestCode: Int,
+    permissions: Array<out String>,
+    grantResults: IntArray
+  ) {
+    super.onRequestPermissionsResult(requestCode, permissions, grantResults)
+    if (grantResults.isEmpty()) {
+      // Empty results are triggered if a permission is requested while another request was already
+      // pending and can be safely ignored in this case.
+      return
+    }
+    if (grantResults[0] != PackageManager.PERMISSION_GRANTED) {
+      Toast.makeText(applicationContext, R.string.notification_permission_denied, Toast.LENGTH_LONG)
+        .show()
+    }
+  }
+
   private fun initializeBrowser() {
     browserFuture =
       MediaBrowser.Builder(

demos/session/src/main/res/values/strings.xml

@@ -21,4 +21,6 @@
   <string name="shuffle">Shuffle</string>
   <string name="play_button">Play</string>
   <string name="waiting_for_metadata">Waiting for playlist to load…</string>
+  <string name="notification_permission_denied">
+    "Without notification access the app can't warn about failed background operations"</string>
 </resources>

demos/session_service/src/main/AndroidManifest.xml

@@ -13,6 +13,8 @@
      See the License for the specific language governing permissions and
      limitations under the License.
 -->
-<manifest  package="androidx.media3.demo.session.service">
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+  package="androidx.media3.demo.session.service">
   <uses-sdk />
+  <uses-permission android:name="android.permission.POST_NOTIFICATIONS"/>
 </manifest>

demos/session_service/src/main/java/androidx/media3/demo/session/DemoPlaybackService.kt

@@ -15,11 +15,12 @@
  */
 package androidx.media3.demo.session
 
-import android.annotation.SuppressLint
+import android.Manifest
 import android.app.NotificationChannel
 import android.app.NotificationManager
 import android.app.PendingIntent
 import android.content.Intent
+import android.content.pm.PackageManager
 import android.os.Build
 import androidx.annotation.OptIn
 import androidx.core.app.NotificationCompat
@@ -136,8 +137,15 @@ open class DemoPlaybackService : MediaLibraryService() {
      * by a media controller to resume playback when the {@link MediaSessionService} is in the
      * background.
      */
-    @SuppressLint("MissingPermission") // TODO: b/280766358 - Request this permission at runtime.
     override fun onForegroundServiceStartNotAllowedException() {
+      if (
+        Build.VERSION.SDK_INT >= 33 &&
+          checkSelfPermission(Manifest.permission.POST_NOTIFICATIONS) !=
+            PackageManager.PERMISSION_GRANTED
+      ) {
+        // Notification permission is required but not granted
+        return
+      }
       val notificationManagerCompat = NotificationManagerCompat.from(this@DemoPlaybackService)
       ensureNotificationChannel(notificationManagerCompat)
       val builder =