Add MemoryCoordinatorImpl

content/browser/memory/memory_coordinator_impl.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 CONTENT_BROWSER_MEMORY_MEMORY_COORDINATOR_IMPL_H_
+#define CONTENT_BROWSER_MEMORY_MEMORY_COORDINATOR_IMPL_H_
+
+#include "base/memory/singleton.h"
+#include "base/single_thread_task_runner.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "content/browser/memory/memory_coordinator.h"
+
+namespace content {
+
+class MemoryMonitor;
+struct MemoryCoordinatorSingletonTraits;
+
+class MemoryCoordinatorImpl : public MemoryCoordinator {
+ public:
+  MemoryCoordinatorImpl(scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+                        std::unique_ptr<MemoryMonitor> monitor);
+  ~MemoryCoordinatorImpl() override;
+
+  void Start() override;
+
+  void OnChildAdded(int render_process_id) override;
+
+ private:
+  friend struct MemoryCoordinatorSingletonTraits;
+
+  // This struct holds some parameters to determine the global state.
+  struct Configuration {
+    int predicted_renderer_size;
+    int pressure_threshold_mb;
+    int num_children_until_throttled;
+    int num_children_until_suspended;
+    base::TimeDelta minimum_transition_period;
+    base::TimeDelta monitoring_iterval;
+  };

[chrisha, 2016/10/04 20:00:53]

Not sure we need a separate struct for this. I'd simply make these constants
that are all defined in the .cc file, defined in the anonymous namespace and
with detailed comments. If we decide to make something configurable, promote it
to a member variable, and add a function for setting the value that can be
overridden / uses Finch / etc.

(This is more in line with the pattern I've seen used across Chrome for such
things.)

[bashi, 2016/10/06 03:55:45]

Changed to put these as member variables (though I think putting them together
in a single struct would be easy to read). I'll add comments when preparing
actual review.

I didn't make these constants because we would want to configure them for finch
or tests.

+
+  using MemoryState = base::MemoryState;
+
+  MemoryState CalculateNextState();
+  void UpdateState();
+  void NotifyStateToClients();
+  void NotifyStateToChildren();
+
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  base::RepeatingTimer timer_;
+  std::unique_ptr<MemoryMonitor> memory_monitor_;
+  Configuration config_;
+  base::MemoryState current_state_ = MemoryState::NORMAL;
+  base::TimeTicks last_state_change_;
+
+  DISALLOW_COPY_AND_ASSIGN(MemoryCoordinatorImpl);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_MEMORY_MEMORY_COORDINATOR_IMPL_H_