[tracing] Add memory statistics from level db clients to tracing.

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 <map>
 #include <string>
 
 #include "base/files/file_path.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/synchronization/lock.h"
+#include "base/trace_event/memory_dump_provider.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 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 :
-    public base::RefCountedThreadSafe<SessionStorageDatabase> {
+class CONTENT_EXPORT SessionStorageDatabase
+    : public base::RefCountedThreadSafe<SessionStorageDatabase>,
+      public base::trace_event::MemoryDumpProvider {
  public:
   explicit SessionStorageDatabase(const base::FilePath& file_path);
 
   // Reads the (key, value) pairs for |namespace_id| and |origin|. |result| is
   // assumed to be empty and any duplicate keys will be overwritten. If the
   // database exists on disk then it will be opened. If it does not exist then
   // it will not be created and |result| will be unmodified.
   void ReadAreaValues(const std::string& namespace_id,
                       const GURL& origin,
                       DOMStorageValuesMap* result);
@@ skipping 17 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);
 
+  // base::trace_event::MemoryDumpProvider implementation.
+  bool OnMemoryDump(const base::trace_event::MemoryDumpArgs& args,
+                    base::trace_event::ProcessMemoryDump* pmd) override;
+
  private:
   friend class base::RefCountedThreadSafe<SessionStorageDatabase>;
   class DBOperation;
   friend class SessionStorageDatabase::DBOperation;
   friend class SessionStorageDatabaseTest;
 
-  ~SessionStorageDatabase();
+  ~SessionStorageDatabase() override;
 
   // 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
   // if the opening failed or was not necessary (the database doesn't exist and
   // |create_if_needed| is false). The possible failures are:
   // - leveldb cannot open the database.
   // - The database is in an inconsistent or errored state.
   bool LazyOpen(bool create_if_needed);
 
   // Tries to open the database at file_path_, assigns |db| to point to the
@@ skipping 113 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_