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

gpu/command_buffer/service/mailbox_synchronizer.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_SYNCHRONIZER_H_
-#define GPU_COMMAND_BUFFER_SERVICE_MAILBOX_SYNCHRONIZER_H_
-
-#include "gpu/command_buffer/common/mailbox.h"
-
-#include <map>
-#include <queue>
-#include <set>
-
-#include "base/memory/linked_ptr.h"
-#include "base/synchronization/lock.h"
-#include "gpu/command_buffer/service/texture_definition.h"
-#include "gpu/gpu_export.h"
-
-namespace gfx {
-class GLFence;
-}
-
-namespace gpu {
-namespace gles2 {
-
-class MailboxManager;
-class Texture;
-
-// A thread-safe proxy that can be used to emulate texture sharing across
-// share-groups.
-class MailboxSynchronizer {
- public:
-  ~MailboxSynchronizer();
-
-  GPU_EXPORT static bool Initialize();
-  GPU_EXPORT static void Terminate();
-  static MailboxSynchronizer* GetInstance();
-
-  // Create a texture from a globally visible mailbox.
-  Texture* CreateTextureFromMailbox(unsigned target, const Mailbox& mailbox);
-
-  void PushTextureUpdates(MailboxManager* manager, uint32 sync_point);
-  void PullTextureUpdates(MailboxManager* manager, uint32 sync_point);
-
-  void TextureDeleted(Texture* texture);
-
- private:
-  MailboxSynchronizer();
-
-  struct TargetName {
-    TargetName(unsigned target, const Mailbox& mailbox);
-    bool operator<(const TargetName& rhs) const {
-      return memcmp(this, &rhs, sizeof(rhs)) < 0;
-    }
-    bool operator!=(const TargetName& rhs) const {
-      return memcmp(this, &rhs, sizeof(rhs)) != 0;
-    }
-    bool operator==(const TargetName& rhs) const {
-      return !operator!=(rhs);
-    }
-    unsigned target;
-    Mailbox mailbox;
-  };
-
-  base::Lock lock_;
-
-  struct TextureGroup {
-    explicit TextureGroup(const TextureDefinition& definition);
-    ~TextureGroup();
-
-    TextureDefinition definition;
-    std::set<TargetName> mailboxes;
-   private:
-    DISALLOW_COPY_AND_ASSIGN(TextureGroup);
-  };
-
-  struct TextureVersion {
-    explicit TextureVersion(linked_ptr<TextureGroup> group);
-    ~TextureVersion();
-
-    unsigned int version;
-    linked_ptr<TextureGroup> group;
-  };
-  typedef std::map<Texture*, TextureVersion> TextureMap;
-  TextureMap textures_;
-
-  linked_ptr<TextureGroup> GetGroupForMailboxLocked(
-      const TargetName& target_name);
-  void ReassociateMailboxLocked(
-      const TargetName& target_name,
-      TextureGroup* group);
-  void UpdateTextureLocked(Texture* texture, TextureVersion& texture_version);
-  void CreateFenceLocked(uint32 sync_point);
-  void AcquireFenceLocked(uint32 sync_point);
-
-  typedef std::map<uint32, linked_ptr<gfx::GLFence> > SyncPointToFenceMap;
-  SyncPointToFenceMap sync_point_to_fence_;
-  std::queue<SyncPointToFenceMap::iterator> sync_points_;
-
-  DISALLOW_COPY_AND_ASSIGN(MailboxSynchronizer);
-};
-
-}  // namespage gles2
-}  // namespace gpu
-
-#endif  // GPU_COMMAND_BUFFER_SERVICE_MAILBOX_SYNCHRONIZER_H_
-