content: Pass IOSurface references using Mach IPC.

content/browser/browser_io_surface_manager_mac.h

+// Copyright 2015 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_BROWSER_IO_SURFACE_MANAGER_MAC_H_
+#define CONTENT_BROWSER_BROWSER_IO_SURFACE_MANAGER_MAC_H_
+
+#include <mach/mach.h>
+
+#include <map>
+#include <set>
+#include <utility>
+
+#include "base/containers/scoped_ptr_hash_map.h"
+#include "base/mac/dispatch_source_mach.h"
+#include "base/mac/scoped_mach_port.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/singleton.h"
+#include "base/synchronization/lock.h"
+#include "content/common/mac/io_surface_manager.h"
+#include "gpu/command_buffer/common/mailbox.h"
+
+namespace content {
+
+// Implementation of IOSurfaceManager that provides a mechanism for child
+// processes to register and acquire IOSurfaces through Mach IPC.
+class CONTENT_EXPORT BrowserIOSurfaceManager : public IOSurfaceManager {
+ public:
+  // Returns the global BrowserIOSurfaceManager.
+  static BrowserIOSurfaceManager* GetInstance();
+
+  // Overridden from IOSurfaceManager:
+  bool RegisterIOSurface(int io_surface_id,
+                         int client_id,
+                         IOSurfaceRef io_surface) override;
+  void UnregisterIOSurface(int io_surface_id, int client_id) override;
+  IOSurfaceRef AcquireIOSurface(int io_surface_id) override;
+
+  // Generate a unique unguessable mailbox name that a child process can use to
+  // acquire IOSurface references.

[Robert Sesek, 2015/05/15 21:45:05]

|client_id| is the ___.

[reveman, 2015/05/18 18:15:38]

Done.

+  gpu::Mailbox GenerateChildProcessMailbox(int client_id);
+
+  // Invalidate a previously generated mailbox name.
+  void InvalidateChildProcessMailbox(const gpu::Mailbox& mailbox);
+
+  // Get a unique unguessable mailbox name that each GPU process can

[Robert Sesek, 2015/05/15 21:45:05]

a -> the, otherwise it's hard to understand why this shouldn't be named
"Generate". Also, isn't there only one GPU process, why "each"?

[reveman, 2015/05/18 18:15:38]

Done. Also changed the language to say "the" instead as that's less confusing.
There can be multiple GPU processes in the sense that if one crashes, we'll
spawn a new process. Maybe some other user of content/ is using multiple GPU
processes at the same time but chrome doesn't. I didn't want to make a 1 gpu
process/service assumption here but it also seemed overkill to try prevent one
gpu process from being able to unregister another GPU process's iosurfaces. 

Current code supports multiple GPU processes if necessary but doesn't keep them
in different IOSurface sandboxes.

+  // use to register/unregister IOSurface for use by clients.
+  gpu::Mailbox GetGpuProcessMailbox() const;
+
+ private:
+  friend struct DefaultSingletonTraits<BrowserIOSurfaceManager>;
+
+  BrowserIOSurfaceManager();
+  ~BrowserIOSurfaceManager() override;
+
+  // Message handler that is invoked on |dispatch_source_| when an
+  // incoming message needs to be received.
+  void HandleRequest();
+
+  // Mach message handlers.
+  void OnRegisterIOSurface(const mach_msg_header_t& header,
+                           int io_surface_id,
+                           int client_id,
+                           mach_port_t io_surface_port,
+                           const gpu::Mailbox& gpu_process_mailbox);
+  void OnUnregisterIOSurface(const mach_msg_header_t& header,
+                             int io_surface_id,
+                             int client_id,
+                             const gpu::Mailbox& gpu_process_mailbox);
+  void OnAcquireIOSurface(const mach_msg_header_t& header,
+                          int io_surface_id,
+                          const gpu::Mailbox& gpu_process_mailbox);
+
+  // The Mach port on which the server listens.
+  base::mac::ScopedMachReceiveRight server_port_;
+
+  // The dispatch source and queue on which Mach messages will be received.
+  scoped_ptr<base::DispatchSourceMach> dispatch_source_;
+
+  // Stores the IOSurfces for all GPU clients.
+  typedef std::pair<int, int> IOSurfaceMapKey;

[Robert Sesek, 2015/05/15 21:45:05]

using IOSurfaceMapKey = std::pair<int, int>;

[reveman, 2015/05/18 18:15:38]

Done.

+  typedef base::ScopedPtrHashMap<IOSurfaceMapKey,

[Robert Sesek, 2015/05/15 21:45:05]

using IOSurfaceMap = ...;

[reveman, 2015/05/18 18:15:38]

Done.

+                                 scoped_ptr<base::mac::ScopedMachSendRight>>
+      IOSurfaceMap;
+  IOSurfaceMap io_surfaces_;
+
+  // Stores the Child process unique id (RenderProcessHost ID) for every
+  // mailbox.
+  typedef std::map<gpu::Mailbox, int> ChildProcessIdMap;
+  ChildProcessIdMap child_process_ids_;
+
+  // Stores the GPU process mailbox.
+  gpu::Mailbox gpu_process_mailbox_;
+
+  // Mutex that guards |io_surfaces_|, |child_process_ids_| and
+  // |gpu_process_mailbox_|.
+  mutable base::Lock lock_;
+
+  DISALLOW_COPY_AND_ASSIGN(BrowserIOSurfaceManager);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_BROWSER_IO_SURFACE_MANAGER_MAC_H_