[tracing] Add a memory dump provider for DOM storage

content/browser/dom_storage/session_storage_database.h

 // Copyright 2013 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 CONTENT_BROWSER_DOM_STORAGE_SESSION_STORAGE_DATABASE_H_
 #define CONTENT_BROWSER_DOM_STORAGE_SESSION_STORAGE_DATABASE_H_
 
 #include <stdint.h>
 
 #include <map>
 #include <memory>
 #include <string>
 
 #include "base/files/file_path.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/synchronization/lock.h"
 #include "content/common/content_export.h"
 #include "content/common/dom_storage/dom_storage_types.h"
 #include "third_party/leveldatabase/src/include/leveldb/status.h"
 
 class GURL;
 
 namespace leveldb {
 class DB;
 struct ReadOptions;
 class WriteBatch;
 }  // namespace leveldb
 
+namespace base {
+namespace trace_event {
+class ProcessMemoryDump;
+}
+}
+
 namespace content {
 
 // SessionStorageDatabase holds the data from multiple namespaces and multiple
 // origins. All DOMStorageAreas for session storage share the same
 // SessionStorageDatabase.
 
 // Only one thread is allowed to call the public functions other than
 // ReadAreaValues and ReadNamespacesAndOrigins. Other threads are allowed to
 // call ReadAreaValues and ReadNamespacesAndOrigins.
 class CONTENT_EXPORT SessionStorageDatabase :
@@ skipping 28 matching lines @@
   // Deletes the data for |namespace_id| and |origin|.
   bool DeleteArea(const std::string& namespace_id, const GURL& origin);
 
   // Deletes the data for |namespace_id|.
   bool DeleteNamespace(const std::string& namespace_id);
 
   // Reads the namespace IDs and origins present in the database.
   bool ReadNamespacesAndOrigins(
       std::map<std::string, std::vector<GURL> >* namespaces_and_origins);
 
+  // Adds memory statistics to |pmd| for chrome://tracing.
+  bool OnMemoryDump(base::trace_event::ProcessMemoryDump* pmd);

[michaeln, 2016/05/02 22:47:12]

maybe remove the return value since it's always |true| and not used at the
callsite anyway

[ssid, 2016/05/04 06:06:14]

Done.

+
  private:
   friend class base::RefCountedThreadSafe<SessionStorageDatabase>;
   class DBOperation;
   friend class SessionStorageDatabase::DBOperation;
   friend class SessionStorageDatabaseTest;
 
   ~SessionStorageDatabase();
 
   // Opens the database at file_path_ if it exists already and creates it if
   // |create_if_needed| is true. Returns true if the database was opened, false
@@ skipping 120 matching lines @@
   // The number of database operations in progress. We need this so that we can
   // delete an inconsistent database at the right moment.
   int operation_count_;
 
   DISALLOW_COPY_AND_ASSIGN(SessionStorageDatabase);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOM_STORAGE_SESSION_STORAGE_DATABASE_H_