Declare all InternalState values in switch statement

Lint likes all constants for an IntDef to be declared explicitly
in switch statements.

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=207545682

library/core/src/main/java/com/google/android/exoplayer2/offline/DownloadManager.java

@@ -730,6 +730,11 @@ public final class DownloadManager {
           return "CANCELING";
         case STATE_STARTED_STOPPING:
           return "STOPPING";
+        case STATE_QUEUED:
+        case STATE_STARTED:
+        case STATE_COMPLETED:
+        case STATE_CANCELED:
+        case STATE_FAILED:
         default:
           return TaskState.getStateString(currentState);
       }
@@ -742,6 +747,11 @@ public final class DownloadManager {
         case STATE_STARTED_CANCELING:
         case STATE_STARTED_STOPPING:
           return STATE_STARTED;
+        case STATE_QUEUED:
+        case STATE_STARTED:
+        case STATE_COMPLETED:
+        case STATE_CANCELED:
+        case STATE_FAILED:
         default:
           return currentState;
       }