UpdateAttempterAndroid::Init initiates merge

On update_engine starts, schedule CleanupPreviousUpdateAction that calls
CleanupSuccessfulUpdate to do necessary cleanup as soon as possible.

In the good case, update_engine initiates merge when
sys.boot_completed, and clean up snapshots.

If the update is
rolled back or partitions are flashed, the following happens (on
a Virtual A/B device):

- UpdateAttempterAndroid::CleanupSuccessfulUpdate is called
  - DynamicPartitionControlAndroid::CleanupSuccessfulUpdate is called
  - SnapshotManager::InitiateMergeAndWait is called
  - SnapshotManager::RemoveAllUpdateState(before_cancel) is called
  - before_cancel is called,
    DeltaPerformer::ResetUpdateProgress is called
    - All update states in update_engine is reset.
  - SnapshotManager proceeds to delete snapshots
    - All update states in SnapshotManager is reset.

Hence, on an VAB device, when an update is rolled back or partitions
are flashed, the whole update needs to be re-applied
(while in A/B, it skips writing and directly start verifying hashes of
the target partitions because the update markers are still there).

Bug: 147696014
Test: apply OTA then reboot, inspect logs and do `snapshotctl dump`

Change-Id: I0fc5e7768dfb53e4fd474f2d8d85d2a1b615a88b

1 files changed, 9 insertions, 0 deletions

diff --git a/common/dynamic_partition_control_stub.cc b/common/dynamic_partition_control_stub.cc
index cc36c5c9..70d6768a 100644
--- a/common/dynamic_partition_control_stub.cc
+++ b/common/dynamic_partition_control_stub.cc
@@ -16,6 +16,7 @@
 
 #include <stdint.h>
 
+#include <memory>
 #include <string>
 
 #include <base/logging.h>
@@ -56,4 +57,12 @@ ErrorCode DynamicPartitionControlStub::CleanupSuccessfulUpdate() {
   return ErrorCode::kError;
 }
 
+std::unique_ptr<AbstractAction>
+DynamicPartitionControlStub::GetCleanupPreviousUpdateAction(
+    BootControlInterface* boot_control,
+    PrefsInterface* prefs,
+    CleanupPreviousUpdateActionDelegateInterface* delegate) {
+  return std::make_unique<NoOpAction>();
+}
+
 }  // namespace chromeos_update_engine