Refactor for ISnapshotWriter removal.

Bug: 280529365
Test: update_engine_unittests
      apply ota
Change-Id: I03e899ba31077f828268be3775ebceba3850c528
diff --git a/common/dynamic_partition_control_interface.h b/common/dynamic_partition_control_interface.h
index 3f735bb..490892e 100644
--- a/common/dynamic_partition_control_interface.h
+++ b/common/dynamic_partition_control_interface.h
@@ -32,7 +32,7 @@
 
 // Forware declare for libsnapshot/snapshot_writer.h
 namespace android::snapshot {
-class ISnapshotWriter;
+class ICowWriter;
 }
 
 namespace chromeos_update_engine {
@@ -166,10 +166,10 @@
   // If `is_append` is false, then existing COW data will be overwritten.
   // Otherwise the cow writer will be opened on APPEND mode, existing COW data
   // is preserved.
-  virtual std::unique_ptr<android::snapshot::ISnapshotWriter> OpenCowWriter(
+  virtual std::unique_ptr<android::snapshot::ICowWriter> OpenCowWriter(
       const std::string& unsuffixed_partition_name,
       const std::optional<std::string>&,
-      bool is_append = false) = 0;
+      std::optional<uint64_t> label) = 0;
   // Open a general purpose FD capable to reading and writing to COW. Note that
   // writes must be block aligned.
   virtual std::unique_ptr<FileDescriptor> OpenCowFd(