Add MemoryCoordinator

components/memory_coordinator/browser/memory_state_notifier.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.
+
+#ifndef COMPONENTS_MEMORY_COORDINATOR_BROWSER_MEMORY_STATE_NOTIFIER_H_
+#define COMPONENTS_MEMORY_COORDINATOR_BROWSER_MEMORY_STATE_NOTIFIER_H_
+
+#include <map>
+#include <memory>
+
+#include "base/threading/non_thread_safe.h"
+#include "components/memory_coordinator/common/memory_coordinator_features.h"
+#include "components/memory_coordinator/public/interfaces/child_memory_coordinator.mojom.h"
+
+namespace memory_coordinator {
+
+// MemoryStateNotifier sends memory events to ChildMemoryCoordinators using
+// mojo messages. This isn't thread-safe.
+class MemoryStateNotifier : public base::NonThreadSafe {
+ public:
+  MemoryStateNotifier();
+  ~MemoryStateNotifier();
+
+  // Add a ChildMemoryCoordinator. MemoryStateNotifier takes the ownership.
+  // A child will be removed when a connection error happens.
+  void AddChild(mojom::ChildMemoryCoordinatorPtr child);
+
+  // Notify a memory event to all ChildMemoryCoordinators.
+  void Notify(mojom::MemoryState state);
+
+  // Iterate all clients and run a given callback.
+  using IterateCallback =
+      base::Callback<void(mojom::ChildMemoryCoordinatorPtr&)>;
+  void IterateChildren(const IterateCallback& callback);
+
+ private:
+  int GetNextId();
+  void RemoveChild(int id);

[chrisha, 2016/06/27 20:35:30]

Documentation for these functions would be helpful for somebody reading the
code. (ie. RemoveChild is used as an on-error callback to remove a child when
the connection dies.)

+
+  int next_id_ = 0;
+  std::map<int, mojom::ChildMemoryCoordinatorPtr> children_;
+
+  DISALLOW_COPY_AND_ASSIGN(MemoryStateNotifier);
+};
+
+}  // namespace memory_coordinator
+
+#endif  // COMPONENTS_MEMORY_COORDINATOR_BROWSER_MEMORY_STATE_NOTIFIER_H_