Aura/ÜC: Drop frames on background tabs

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 <list>
+#include <set>
+
+#include "base/basictypes.h"
+#include "base/memory/singleton.h"
+#include "content/common/content_export.h"
+
+namespace content {
+
+class CONTENT_EXPORT RendererFrameManagerClient {
+ public:
+  virtual ~RendererFrameManagerClient() {}
+  virtual void EvictCurrentFrame() = 0;
+};
+
+class CONTENT_EXPORT RendererFrameManager {
+ public:
+  static RendererFrameManager* GetInstance();
+
+  void AddFrame(RendererFrameManagerClient*, bool visible);
+  void RemoveFrame(RendererFrameManagerClient*);
+  void SetFrameVisibility(RendererFrameManagerClient*, bool visible);
+
+  size_t max_number_of_saved_frames() const {
+    return max_number_of_saved_frames_;
+  }
+
+ private:
+  RendererFrameManager();
+  ~RendererFrameManager();
+  void CullHiddenFrames();
+  friend struct DefaultSingletonTraits<RendererFrameManager>;
+
+  std::set<RendererFrameManagerClient*> visible_frames_;
+  std::list<RendererFrameManagerClient*> hidden_frames_;
+  size_t max_number_of_saved_frames_;
+
+  DISALLOW_COPY_AND_ASSIGN(RendererFrameManager);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_RENDERER_FRAME_MANAGER_H_