Add UMA histograms to mojo leveldb env

components/leveldb/env_mojo.h

 // 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.
 
 #ifndef COMPONENTS_LEVELDB_ENV_MOJO_H_
 #define COMPONENTS_LEVELDB_ENV_MOJO_H_
 
 #include "components/filesystem/public/interfaces/directory.mojom.h"
 #include "components/leveldb/leveldb_mojo_proxy.h"
+#include "third_party/leveldatabase/env_chromium.h"
 #include "third_party/leveldatabase/src/include/leveldb/env.h"
 
 namespace leveldb {
 
 // An implementation of the leveldb operating system interaction code which
 // proxies to a specified mojo:filesystem directory. Most of these methods are
 // synchronous and block on responses from the filesystem service. That's fine
 // since, for the most part, they merely open files or check for a file's
 // existence.
-class MojoEnv : public leveldb::Env {
+class MojoEnv : public Env, public leveldb_env::UMALogger {
  public:
   MojoEnv(scoped_refptr<LevelDBMojoProxy> file_thread,
           LevelDBMojoProxy::OpaqueDir* dir);
   ~MojoEnv() override;
 
   // Overridden from leveldb::Env:
   Status NewSequentialFile(const std::string& fname,
                            SequentialFile** result) override;
   Status NewRandomAccessFile(const std::string& fname,
                              RandomAccessFile** result) override;
@@ skipping 13 matching lines @@
   Status UnlockFile(FileLock* lock) override;
   Status GetTestDirectory(std::string* path) override;
   Status NewLogger(const std::string& fname, Logger** result) override;
 
   uint64_t NowMicros() override;
   void SleepForMicroseconds(int micros) override;
   void Schedule(void (*function)(void* arg), void* arg) override;
   void StartThread(void (*function)(void* arg), void* arg) override;
 
  private:
+  void RecordErrorAt(leveldb_env::MethodID method) const override;
+  void RecordOSError(leveldb_env::MethodID method,
+                     base::File::Error error) const override;
+
+  void RecordFileError(leveldb_env::MethodID method,
+                       filesystem::mojom::FileError error) const;
+
   scoped_refptr<LevelDBMojoProxy> thread_;
   LevelDBMojoProxy::OpaqueDir* dir_;
 
   DISALLOW_COPY_AND_ASSIGN(MojoEnv);
 };
 
 }  // namespace leveldb
 
 #endif  // COMPONENTS_LEVELDB_ENV_MOJO_H_