update_engine: use cow_size_info

Updating update_engine to use a struct called CowSizeInfo which contains
extra parameters needed in v3 of cow format. These fields should be set
in delta archive manifest and passed to snapshot.cpp which will then
use the fields to correctly configure the cow with a correctly sized
operation buffer space.

Test: ota on cuttlefish
Change-Id: I8306bf3e4bbc3fcd8f2e31be116fa0623022c227
diff --git a/download_action_android_unittest.cc b/download_action_android_unittest.cc
index 968f875..426d7fd 100644
--- a/download_action_android_unittest.cc
+++ b/download_action_android_unittest.cc
@@ -102,8 +102,8 @@
   ftruncate(partition_file.fd(), 4096);
   partition_config.size = 4096;
   partition_config.path = partition_file.path();
-  ASSERT_TRUE(
-      payload_file.AddPartition(partition_config, partition_config, {}, {}, 0));
+  ASSERT_TRUE(payload_file.AddPartition(
+      partition_config, partition_config, {}, {}, {}));
   ScopedTempFile blob_file("Blob-XXXXXX");
   ScopedTempFile manifest_file("Manifest-XXXXXX");
   uint64_t metadata_size;