For #7364 - Adds sessionId to DownloadState and populates it in DownloadFeature

Author: codrut.topliceanu

components/browser/state/src/main/java/mozilla/components/browser/state/state/content/DownloadState.kt

@@ -22,6 +22,8 @@ import kotlin.random.Random
  * @property referrerUrl The site that linked to this download.
  * @property skipConfirmation Whether or not the confirmation dialog should be shown before the download begins.
  * @property id The unique identifier of this download.
+ * @property sessionId Identifier of the session that spawned the download.
+ * @
  */
 @Suppress("Deprecation")
 @Parcelize
@@ -34,7 +36,8 @@ data class DownloadState(
     val destinationDirectory: String = Environment.DIRECTORY_DOWNLOADS,
     val referrerUrl: String? = null,
     val skipConfirmation: Boolean = false,
-    val id: Long = Random.nextLong()
+    val id: Long = Random.nextLong(),
+    val sessionId: String? = null
 ) : Parcelable {
     val filePath: String get() =
         Environment.getExternalStoragePublicDirectory(destinationDirectory).path + "/" + fileName

components/feature/downloads/src/main/java/mozilla/components/feature/downloads/DownloadsFeature.kt

@@ -93,9 +93,8 @@ class DownloadsFeature(
             flow.mapNotNull { state -> state.findTabOrCustomTabOrSelectedTab(tabId) }
                 .ifChanged { it.content.download }
                 .collect { state ->
-                    val download = state.content.download
-                    if (download != null) {
-                        processDownload(state, download)
+                    state.content.download?.let { downloadState ->
+                        processDownload(state, downloadState.copy(sessionId = state.id))
                     }
                 }
         }