Update from chromium https://crrev.com/301315

gpu/command_buffer/service/mailbox_manager_impl.h

+// Copyright 2014 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 GPU_COMMAND_BUFFER_SERVICE_MAILBOX_MANAGER_IMPL_H_
+#define GPU_COMMAND_BUFFER_SERVICE_MAILBOX_MANAGER_IMPL_H_
+
+#include <map>
+#include <utility>
+
+#include "base/memory/linked_ptr.h"
+#include "base/memory/ref_counted.h"
+#include "gpu/command_buffer/common/constants.h"
+#include "gpu/command_buffer/common/mailbox.h"
+#include "gpu/command_buffer/service/mailbox_manager.h"
+#include "gpu/gpu_export.h"
+
+namespace gpu {
+namespace gles2 {
+
+class Texture;
+class TextureManager;
+
+// Manages resources scoped beyond the context or context group level.
+class GPU_EXPORT MailboxManagerImpl : public MailboxManager {
+ public:
+  MailboxManagerImpl();
+
+  // MailboxManager implementation:
+  Texture* ConsumeTexture(const Mailbox& mailbox) override;
+  void ProduceTexture(const Mailbox& mailbox, Texture* texture) override;
+  bool UsesSync() override;
+  void PushTextureUpdates(uint32 sync_point) override {}
+  void PullTextureUpdates(uint32 sync_point) override {}
+  void TextureDeleted(Texture* texture) override;
+
+ protected:
+  ~MailboxManagerImpl() override;
+
+ private:
+  friend class base::RefCounted<MailboxManager>;
+
+  void InsertTexture(const Mailbox& mailbox, Texture* texture);
+
+  // This is a bidirectional map between mailbox and textures. We can have
+  // multiple mailboxes per texture, but one texture per mailbox. We keep an
+  // iterator in the MailboxToTextureMap to be able to manage changes to
+  // the TextureToMailboxMap efficiently.
+  typedef std::multimap<Texture*, Mailbox> TextureToMailboxMap;
+  typedef std::map<Mailbox, TextureToMailboxMap::iterator>
+      MailboxToTextureMap;
+
+  MailboxToTextureMap mailbox_to_textures_;
+  TextureToMailboxMap textures_to_mailboxes_;
+
+  DISALLOW_COPY_AND_ASSIGN(MailboxManagerImpl);
+};
+
+}  // namespage gles2
+}  // namespace gpu
+
+#endif  // GPU_COMMAND_BUFFER_SERVICE_MAILBOX_MANAGER_IMPL_H_
+