memory coordinator: Set variation parameters if available

content/public/browser/memory_coordinator_delegate.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_PUBLIC_BROWSER_MEMORY_COORDINATOR_DELEGATE_H_
 #define CONTENT_PUBLIC_BROWSER_MEMORY_COORDINATOR_DELEGATE_H_
 
 #include "content/common/content_export.h"
 
 namespace content {
 
+// Parameters for memory coordinator V0.
+struct MemoryCoordinatorV0Params {

[bashi, 2016/11/18 20:07:27]

Exposing the details is bad, but I couldn't find a way to avoid it.

+  // The median size of a renderer on the current platform. This is used to
+  // convert the amount of free memory to an expected number of new renderers
+  // that could be started before hitting critical memory pressure.
+  int expected_renderer_size;
+  // When in a NORMAL state and the potential number of new renderers drops
+  // below this level, the coordinator will transition to a THROTTLED state.
+  int new_renderers_until_throttled;
+  // When in a NORMAL/THROTTLED state and the potential number of new renderers
+  // drops below this level, the coordinator will transition to a SUSPENDED
+  // state.
+  int new_renderers_until_suspended;
+  // When in a THROTTLED/SUSPENDED state and the potential number of new
+  // renderers rises above this level, the coordinator will transition to a
+  // NORMAL state.
+  int new_renderers_back_to_normal;
+  // When in a SUSPENDED state and the potential number of new renderers rises
+  // above this level, the coordinator will transition to a SUSPENDED state.
+  int new_renderers_back_to_throttled;
+  // The memory coordinator stays in the same state at least this duration even
+  // when there are considerable changes in the amount of free memory to prevent
+  // thrashing.
+  base::TimeDelta minimum_transition_period;
+  // The interval of checking the amount of free memory.
+  base::TimeDelta monitoring_interval;
+};
+
 // A delegate class which is used by the memory coordinator.
 class CONTENT_EXPORT MemoryCoordinatorDelegate {
  public:
   virtual ~MemoryCoordinatorDelegate() {}
 
   // Returns true when a given backgrounded renderer process can be suspended.
   virtual bool CanSuspendBackgroundedRenderer(int render_process_id) = 0;
+
+  // Overrides memory coordinator parameters if variations are available.
+  virtual void OverrideParameters(MemoryCoordinatorV0Params* params) = 0;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_MEMORY_COORDINATOR_DELEGATE_H_