[tracing] Memory dump provider for leveldb_proto

components/leveldb_proto/leveldb_database.h

 // Copyright 2014 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_PROTO_LEVELDB_DATABASE_H_
 #define COMPONENTS_LEVELDB_PROTO_LEVELDB_DATABASE_H_
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/strings/string_split.h"
 #include "base/threading/thread_collision_warner.h"
+#include "base/trace_event/memory_dump_provider.h"
 
 namespace base {
 class HistogramBase;
 }  // namespace base
 
 namespace leveldb {
 class DB;
 class Env;
 struct Options;
 }  // namespace leveldb
 
 namespace leveldb_proto {
 
 // Interacts with the LevelDB third party module.
 // Once constructed, function calls and destruction should all occur on the
 // same thread (not necessarily the same as the constructor).
-class LevelDB {
+class LevelDB : base::trace_event::MemoryDumpProvider {
  public:
   // Constructor. Does *not* open a leveldb - only initialize this class.
   // |client_name| is the name of the "client" that owns this instance. Used
   // for UMA statics as so: LevelDB.<value>.<client name>. It is best to not
   // change once shipped.
   explicit LevelDB(const char* client_name);
-  virtual ~LevelDB();
+  ~LevelDB() override;
 
   virtual bool InitWithOptions(const base::FilePath& database_dir,
                                const leveldb::Options& options);
   virtual bool Init(const base::FilePath& database_dir);
   virtual bool Save(const base::StringPairs& pairs_to_save,
                     const std::vector<std::string>& keys_to_remove);
   virtual bool Load(std::vector<std::string>* entries);
   virtual bool Get(const std::string& key, bool* found, std::string* entry);
 
   static bool Destroy(const base::FilePath& database_dir);
 
+  // base::trace_event::MemoryDumpProvider implementation.
+  bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& dump_args,
+                    base::trace_event::ProcessMemoryDump* pmd) override;
+
  private:
   DFAKE_MUTEX(thread_checker_);
 
   // The declaration order of these members matters: |db_| depends on |env_| and
   // therefore has to be destructed first.
   std::unique_ptr<leveldb::Env> env_;
   std::unique_ptr<leveldb::DB> db_;
   base::HistogramBase* open_histogram_;
+  // Name of the client shown in chrome://tracing.
+  std::string client_name_;
 
   DISALLOW_COPY_AND_ASSIGN(LevelDB);
 };
 
 }  // namespace leveldb_proto
 
 #endif  // COMPONENTS_LEVELDB_PROTO_LEVELDB_DATABASE_H_