libsnapshot: Fix some minor formatting bugs

A few minor issues snuck through code review.
Removed a debug line in cow_api_test to persist file.
Removed unused function declaration for cow writer
Switched PLOG to LOG where no errno exists.

Change-Id: Ibb774d6de518fc2a8746e4b9eefc3655c9973c30
Bug: 168554689
Test: cow_api_test
diff --git a/fs_mgr/libsnapshot/cow_api_test.cpp b/fs_mgr/libsnapshot/cow_api_test.cpp
index 3d0321f..1408244 100644
--- a/fs_mgr/libsnapshot/cow_api_test.cpp
+++ b/fs_mgr/libsnapshot/cow_api_test.cpp
@@ -272,7 +272,6 @@
 }
 
 TEST_F(CowTest, Append) {
-    cow_->DoNotRemove();
     CowOptions options;
     auto writer = std::make_unique<CowWriter>(options);
     ASSERT_TRUE(writer->Initialize(cow_->fd));
diff --git a/fs_mgr/libsnapshot/cow_writer.cpp b/fs_mgr/libsnapshot/cow_writer.cpp
index ec2dc96..f2692dc 100644
--- a/fs_mgr/libsnapshot/cow_writer.cpp
+++ b/fs_mgr/libsnapshot/cow_writer.cpp
@@ -247,7 +247,7 @@
     }
 
     if (!found_label) {
-        PLOG(ERROR) << "Failed to find last label";
+        LOG(ERROR) << "Failed to find last label";
         return false;
     }
 
diff --git a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
index c031d63..0f47622 100644
--- a/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
+++ b/fs_mgr/libsnapshot/include/libsnapshot/cow_writer.h
@@ -114,7 +114,6 @@
     bool OpenForWrite();
     bool OpenForAppend();
     bool OpenForAppend(uint64_t label);
-    bool ImportOps(std::unique_ptr<ICowOpIter> iter);
     bool GetDataPos(uint64_t* pos);
     bool WriteRawData(const void* data, size_t size);
     bool WriteOperation(const CowOperation& op, const void* data = nullptr, size_t size = 0);