Make RendererFrameManager a client of memory coordinator

content/browser/renderer_host/renderer_frame_manager.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_RENDERER_HOST_RENDERER_FRAME_MANAGER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_RENDERER_FRAME_MANAGER_H_
 
 #include <stddef.h>
 
 #include <list>
 #include <map>
 
 #include "base/macros.h"
+#include "base/memory/memory_coordinator_client.h"
 #include "base/memory/memory_pressure_listener.h"
 #include "base/memory/singleton.h"
 #include "content/common/content_export.h"
 
 namespace content {
 
 class RenderWidgetHostViewAuraTest;
 
 class CONTENT_EXPORT RendererFrameManagerClient {
  public:
   virtual ~RendererFrameManagerClient() {}
   virtual void EvictCurrentFrame() = 0;
 };
 
 // This class is responsible for globally managing which renderers keep their
 // compositor frame when offscreen. We actively discard compositor frames for
 // offscreen tabs, but keep a minimum amount, as an LRU cache, to make switching
 // between a small set of tabs faster. The limit is a soft limit, because
 // clients can lock their frame to prevent it from being discarded, e.g. if the
 // tab is visible, or while capturing a screenshot.
-class CONTENT_EXPORT RendererFrameManager {
+class CONTENT_EXPORT RendererFrameManager :
+    public base::MemoryCoordinatorClient {
  public:
   static RendererFrameManager* GetInstance();
 
   void AddFrame(RendererFrameManagerClient*, bool locked);
   void RemoveFrame(RendererFrameManagerClient*);
   void LockFrame(RendererFrameManagerClient*);
   void UnlockFrame(RendererFrameManagerClient*);
 
   size_t GetMaxNumberOfSavedFrames() const;
 
   // For testing only
   void set_max_number_of_saved_frames(size_t max_number_of_saved_frames) {
     max_number_of_saved_frames_ = max_number_of_saved_frames;
   }
   void set_max_handles(float max_handles) { max_handles_ = max_handles; }
 
  private:
   // Please remove when crbug.com/443824 has been fixed.
   friend class RenderWidgetHostViewAuraTest;
 
   RendererFrameManager();
-  ~RendererFrameManager();
+  ~RendererFrameManager() override;
+
+  // base::MemoryCoordinatorClient implementation:
+  void OnMemoryStateChange(base::MemoryState state) override;
+
   void CullUnlockedFrames(size_t saved_frame_limit);
 
   // React on memory pressure events to adjust the number of cached frames.
   void OnMemoryPressure(
       base::MemoryPressureListener::MemoryPressureLevel memory_pressure_level);
 
+  void PurgeMemory(int percentage);
+
   friend struct base::DefaultSingletonTraits<RendererFrameManager>;
 
   // Listens for system under pressure notifications and adjusts number of
   // cached frames accordingly.
-  base::MemoryPressureListener memory_pressure_listener_;
+  std::unique_ptr<base::MemoryPressureListener> memory_pressure_listener_;
 
   std::map<RendererFrameManagerClient*, size_t> locked_frames_;
   std::list<RendererFrameManagerClient*> unlocked_frames_;
   size_t max_number_of_saved_frames_;
   float max_handles_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererFrameManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_RENDERER_FRAME_MANAGER_H_