mojo leveldb: Address some comments that came after it was put in the CQ.

components/leveldb/env_mojo.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/leveldb/env_mojo.h"
 
 #include "base/trace_event/trace_event.h"
 #include "third_party/leveldatabase/chromium_logger.h"
 #include "third_party/leveldatabase/src/include/leveldb/status.h"
 
@@ skipping 25 matching lines @@
            method, MethodIDToString(method));
   return Status::IOError(filename, buf);
 }
 
 class MojoFileLock : public FileLock {
  public:
   MojoFileLock(LevelDBFileThread::OpaqueLock* lock, const std::string& name)
       : fname_(name), lock_(lock) {}
   ~MojoFileLock() override { DCHECK(!lock_); }
 
-  const std::string& name() { return fname_; }
+  const std::string& name() const { return fname_; }
 
   LevelDBFileThread::OpaqueLock* TakeLock() {
     LevelDBFileThread::OpaqueLock* to_return = lock_;
     lock_ = nullptr;
     return to_return;
   }
 
  private:
   std::string fname_;
   LevelDBFileThread::OpaqueLock* lock_;
@@ skipping 112 matching lines @@
 
   leveldb::Status Sync() override {
     TRACE_EVENT0("leveldb", "MojoWritableFile::Sync");
 
     if (!file_.Flush()) {
       base::File::Error error = LastFileError();
       return MakeIOError(filename_, base::File::ErrorToString(error),
                          leveldb_env::kWritableFileSync, error);
     }
 
-    // TODO(erg): In the leveldb_env::ChromiumEnv, there is a whole system
-    // which makes backups of the data here. crbug.com/587185
-
     // leveldb's implicit contract for Sync() is that if this instance is for a
     // manifest file then the directory is also sync'ed. See leveldb's
     // env_posix.cc.
     if (file_type_ == kManifest)
       return SyncParent();
 
     return Status::OK();
   }
 
  private:
@@ skipping 180 matching lines @@
     *result = NULL;
     return MakeIOError(fname, "Unable to create log file",
                        leveldb_env::kNewLogger, f->error_details());
   } else {
     *result = new leveldb::ChromiumLogger(f.release());
     return Status::OK();
   }
 }
 
 }  // namespace leveldb