libsnapshot: remove hard coded cow version

Remove hard coded global variables referencing cow version in
libsnapshot. This value should stem from the build system, or set
individually in test cases.

Bug: 307452468
Test: th
Change-Id: I3d536246008acca92cd93e77886e5f7d17a131e0
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
index 6a7153d..991e17c 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_format.h
@@ -31,15 +31,9 @@
 static constexpr uint32_t kCowVersionMajor = 2;
 static constexpr uint32_t kCowVersionMinor = 0;
 
-static constexpr uint32_t kCowVersionManifest = 2;
-
 static constexpr uint32_t kMinCowVersion = 1;
 static constexpr uint32_t kMaxCowVersion = 3;
 
-// Normally, this should be kMaxCowVersion. When a new version is under testing
-// it may be the previous value of kMaxCowVersion.
-static constexpr uint32_t kDefaultCowVersion = 2;
-
 // This header appears as the first sequence of bytes in the COW. All fields
 // in the layout are little-endian encoded. The on-disk layout is:
 //
diff --git a/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader_test.cpp b/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader_test.cpp
index 10cb06d..f00f236 100644
--- a/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader_test.cpp
+++ b/fs_mgr/libsnapshot/libsnapshot_cow/snapshot_reader_test.cpp
@@ -184,7 +184,7 @@
     unique_fd cow_fd(dup(cow_->fd));
     ASSERT_GE(cow_fd, 0);
 
-    auto writer = CreateCowWriter(kDefaultCowVersion, options, std::move(cow_fd));
+    auto writer = CreateCowWriter(2, options, std::move(cow_fd));
     ASSERT_NO_FATAL_FAILURE(WriteCow(writer.get()));
     ASSERT_NO_FATAL_FAILURE(TestReads(writer.get()));
 }
diff --git a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_test.cpp b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_test.cpp
index d05df82..56f7b59 100644
--- a/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_test.cpp
+++ b/fs_mgr/libsnapshot/snapuserd/user-space-merge/snapuserd_test.cpp
@@ -135,7 +135,7 @@
     unique_fd fd(cow_system_->fd);
     cow_system_->fd = -1;
 
-    return CreateCowWriter(kDefaultCowVersion, options, std::move(fd));
+    return CreateCowWriter(2, options, std::move(fd));
 }
 
 std::unique_ptr<ICowWriter> SnapuserdTestBase::CreateV3Cow() {