[IndexedDB] Propogating changes to observers : Renderer

content/browser/indexed_db/indexed_db_observer_changes.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.
+
+// This class holds all observed operations of a transaction corresponding to a

[jsbell, 2016/07/14 20:08:13]

Move this comment down to just above class {} 

[palakj1, 2016/07/15 20:16:04]

Done.

+// single connection.
+
+#ifndef CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_OBSERVER_CHANGES_H_
+#define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_OBSERVER_CHANGES_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <map>
+#include <set>
+#include <vector>
+
+#include "base/macros.h"
+#include "base/memory/ptr_util.h"
+#include "base/stl_util.h"
+#include "content/browser/indexed_db/indexed_db_observation.h"
+#include "content/common/content_export.h"
+
+namespace content {
+
+class IndexedDBObservation;
+
+class CONTENT_EXPORT IndexedDBObserverChanges {
+ public:
+  IndexedDBObserverChanges();
+  ~IndexedDBObserverChanges();
+
+  void RecordObserverForLastObservation(int32_t observer_id);
+  void AddObservation(std::unique_ptr<IndexedDBObservation> observation);
+
+  std::map<int32_t, std::vector<int32_t>> release_observation_indices_map() {

[cmumford, 2016/07/14 21:11:35]

Are observation_indices_map_ and observations_ linked? If one is released and
the other is not are we going to get into trouble?

[palakj1, 2016/07/15 20:16:04]

We use observation_indices_map to retrieve an index idx and look into
observations_[idx] . They do not hold any reference to each other. 
The release happens only when we are sending an ipc callback message in
IndexedDBDispatcherHost::ConvertObserverChanges.
observation_indices_map_ is released first and then observations_. 
Would that be an issue?

+    return std::move(observation_indices_map_);
+  }
+  std::vector<std::unique_ptr<IndexedDBObservation>> release_observations() {
+    return std::move(observations_);
+  }
+
+ private:
+  // Maps observer_id to corresponding set of indices in observations.
+  std::map<int32_t, std::vector<int32_t>> observation_indices_map_;
+  std::vector<std::unique_ptr<IndexedDBObservation>> observations_;
+
+  DISALLOW_COPY_AND_ASSIGN(IndexedDBObserverChanges);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_OBSERVER_CHANGES_H_