Add DynamicPartitionControlInterface::UpdateUsesSnapshotCompression

This function returns whether Virtual A/B
compression is enabled for the ongoing update.

Test: TH
Bug: 178732971
Change-Id: I781802443afd1d8deac046a8da198658220f7ba0
diff --git a/common/mock_dynamic_partition_control.h b/common/mock_dynamic_partition_control.h
index 3cbf9be..a00ec61 100644
--- a/common/mock_dynamic_partition_control.h
+++ b/common/mock_dynamic_partition_control.h
@@ -79,6 +79,7 @@
               (uint32_t, uint32_t, const std::vector<std::string>&),
               (override));
   MOCK_METHOD(bool, IsDynamicPartition, (const std::string&), (override));
+  MOCK_METHOD(bool, UpdateUsesSnapshotCompression, (), (override));
 };
 
 }  // namespace chromeos_update_engine