partitionmanager: support delayed adopted storage mount

* On some devices, the external mmc driver will only load the card after
  a certain delay. The original code will break and fail to mount any
  adopted storage in this case.

* Add a special fstab flag to allow the partitionmanager to retry after
  a delay.

Change-Id: I219978850ff3ba7ad9dc7ca96fc30634c9574164
diff --git a/partitionmanager.cpp b/partitionmanager.cpp
index 8973782..857ed99 100755
--- a/partitionmanager.cpp
+++ b/partitionmanager.cpp
@@ -2959,6 +2959,16 @@
 	}
 	std::vector<TWPartition*>::iterator adopt;
 	for (adopt = Partitions.begin(); adopt != Partitions.end(); adopt++) {
+		if ((*adopt)->Removable && !(*adopt)->Is_Present && (*adopt)->Adopted_Mount_Delay > 0) {
+			// On some devices, the external mmc driver takes some time
+			// to recognize the card, in which case the "actual block device"
+			// would not have been found yet. We wait the specified delay
+			// and then try again.
+			LOGINFO("Sleeping %d seconds for adopted storage.\n", (*adopt)->Adopted_Mount_Delay);
+			sleep((*adopt)->Adopted_Mount_Delay);
+			(*adopt)->Find_Actual_Block_Device();
+		}
+
 		if ((*adopt)->Removable && (*adopt)->Is_Present) {
 			if ((*adopt)->Decrypt_Adopted() == 0) {
 				ret = true;