Fix lifetime of leveldb::MojoEnv instances.

components/leveldb/leveldb_mojo_proxy.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_LEVELDB_MOJO_PROXY_H_
 #define COMPONENTS_LEVELDB_LEVELDB_MOJO_PROXY_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 19 matching lines @@
 // thread. Because of this mismatch, we create a proxy object which will
 // redirect calls to the thread which owns the Mojo pipe, sends and receives
 // messages.
 //
 // All public methods can be accessed from any thread.
 class LevelDBMojoProxy : public base::RefCountedThreadSafe<LevelDBMojoProxy> {
  public:
   explicit LevelDBMojoProxy(
       scoped_refptr<base::SingleThreadTaskRunner> task_runner);
 
+  base::SingleThreadTaskRunner* task_runner() const {
+    return task_runner_.get();
+  }
+
   // A private struct to hide the underlying file that holds the lock from our
   // callers, forcing them to go through our LockFile()/UnlockFile() interface
   // so that they don't try to use the underlying pointer from an unsafe thread.
   struct OpaqueLock;
 
   // A private struct to hide the underlying root directory that we're
   // operating in. LevelDBMojoProxy will want to own all the directory
   // pointers, so while opening a database, we pass the directory to the thread
   // it will be operated on.
   struct OpaqueDir;
@@ skipping 107 matching lines @@
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
   int outstanding_opaque_dirs_;
 
   DISALLOW_COPY_AND_ASSIGN(LevelDBMojoProxy);
 };
 
 }  // namespace leveldb
 
 #endif  // COMPONENTS_LEVELDB_LEVELDB_MOJO_PROXY_H_