Fix lifetime of leveldb::MojoEnv instances.

components/leveldb/env_mojo.h

Index: components/leveldb/env_mojo.h
diff --git a/components/leveldb/env_mojo.h b/components/leveldb/env_mojo.h
index d784803324321735652be12bd77c44540a4ae91b..80d7ff0290a323561bad19e4e565f81568e3a10b 100644
--- a/components/leveldb/env_mojo.h
+++ b/components/leveldb/env_mojo.h
@@ -5,6 +5,7 @@
 #ifndef COMPONENTS_LEVELDB_ENV_MOJO_H_
 #define COMPONENTS_LEVELDB_ENV_MOJO_H_
 
+#include "base/id_map.h"
 #include "components/filesystem/public/interfaces/directory.mojom.h"
 #include "components/leveldb/leveldb_mojo_proxy.h"
 #include "third_party/leveldatabase/env_chromium.h"
@@ -19,10 +20,13 @@ namespace leveldb {
 // existence.
 class MojoEnv : public leveldb_env::ChromiumEnv {
  public:
-  MojoEnv(const std::string& name,
-          scoped_refptr<LevelDBMojoProxy> file_thread,
-          LevelDBMojoProxy::OpaqueDir* dir);
-  ~MojoEnv() override;
+  static MojoEnv* Get(
+      scoped_refptr<base::SingleThreadTaskRunner> file_task_runner);
+
+  // Registers a |directory| with the leveldb environment, returning a string
+  // that should be used as prefix to indicate files in that directory.
+  std::string RegisterDirectory(filesystem::mojom::DirectoryPtr directory);
+  void UnregisterDirectory(base::StringPiece prefix);
 
   // Overridden from leveldb_env::EnvChromium:
   Status NewSequentialFile(const std::string& fname,
@@ -50,8 +54,15 @@ class MojoEnv : public leveldb_env::ChromiumEnv {
   // NowMicros() or SleepForMicroseconds() and use the EnvChromium versions.
 
  private:
+  MojoEnv(scoped_refptr<base::SingleThreadTaskRunner> file_task_runner);
+  ~MojoEnv() override;
+
+  void ParsePath(const std::string& path,
+                 LevelDBMojoProxy::OpaqueDir** out_dir,
+                 std::string* out_path);
+
   scoped_refptr<LevelDBMojoProxy> thread_;
-  LevelDBMojoProxy::OpaqueDir* dir_;
+  IDMap<LevelDBMojoProxy::OpaqueDir*> dirs_;
 
   DISALLOW_COPY_AND_ASSIGN(MojoEnv);
 };