Implement the functions in CowMergeOperations

Implement the function to create an object & validate sequence.

Bug: 162274240
Test: unit tests pass
Change-Id: Id41460a886d94a98e154b222c3401a5f95b9e047
diff --git a/Android.bp b/Android.bp
index 751e355..e5f0dd8 100644
--- a/Android.bp
+++ b/Android.bp
@@ -696,6 +696,7 @@
         "payload_generator/fake_filesystem.cc",
         "payload_generator/full_update_generator_unittest.cc",
         "payload_generator/mapfile_filesystem_unittest.cc",
+        "payload_generator/merge_sequence_generator_unittest.cc",
         "payload_generator/payload_file_unittest.cc",
         "payload_generator/payload_generation_config_android_unittest.cc",
         "payload_generator/payload_generation_config_unittest.cc",