[Media>UI] Reset media session actions when navigating away

chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java

Index: chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java b/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java
index 080fbf78f108f191da5baf84a90b7414e444e816..11431f7beb7bee32534ffb39b6df0e81513136a2 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/media/ui/MediaNotificationManager.java
@@ -546,6 +546,15 @@ public class MediaNotificationManager {
         return manager.mNotificationBuilder;
     }
 
+    @VisibleForTesting
+    @Nullable
+    static MediaNotificationInfo getMediaNotificationInfoForTesting(
+            int notificationId) {
+        MediaNotificationManager manager = getManager(notificationId);
+
+        return (manager == null) ? null : manager.mMediaNotificationInfo;
+    }
+
     private static boolean isRunningN() {
         return Build.VERSION.SDK_INT >= Build.VERSION_CODES.N;
     }