content: Pass IOSurface references using Mach IPC.

content/browser/mach_broker_mac.h

 // Copyright (c) 2012 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_MACH_BROKER_MAC_H_
 #define CONTENT_BROWSER_MACH_BROKER_MAC_H_
 
 #include <mach/mach.h>
 
 #include <map>
@@ skipping 26 matching lines @@
 class CONTENT_EXPORT MachBroker : public base::ProcessMetrics::PortProvider,
                                   public BrowserChildProcessObserver,
                                   public NotificationObserver {
  public:
   // For use in child processes. This will send the task port of the current
   // process over Mach IPC to the port registered by name (via this class) in
   // the parent process. Returns true if the message was sent successfully
   // and false if otherwise.
   static bool ChildSendTaskPortToParent();
 
+  // Register an IO surface for use in child process with |client_id|.
+  static bool ChildRegisterIOSurfaceWithParent(int io_surface_id,
+                                               int client_id,
+                                               mach_port_t io_surface_port);
+
+  // Unregister an IO surface.
+  static bool ChildUnregisterIOSurfaceWithParent(int io_surface_id,
+                                                 int client_id);
+
+  // Acquire IO surface reference for a registered IO surface. This will only
+  // succeed if the IO surface has been registered for use in the current
+  // process.

[Daniele Castagna, 2015/05/08 18:58:30]

What happens if it doesn't succeed? Does it return MACH_PORT_NULL?

[reveman, 2015/05/09 15:54:54]

Yes, added this to the comment.

+  static mach_port_t ChildAcquireIOSurfaceFromParent(int io_surface_id);
+
   // Returns the global MachBroker.
   static MachBroker* GetInstance();
 
   // The lock that protects this MachBroker object.  Clients MUST acquire and
   // release this lock around calls to EnsureRunning(), PlaceholderForPid(),
   // and FinalizePid().
   base::Lock& GetLock();
 
   // Performs any necessary setup that cannot happen in the constructor.
   // Callers MUST acquire the lock given by GetLock() before calling this
   // method (and release the lock afterwards).
   void EnsureRunning();
 
   // Adds a placeholder to the map for the given pid with MACH_PORT_NULL.
   // Callers are expected to later update the port with FinalizePid().  Callers
   // MUST acquire the lock given by GetLock() before calling this method (and
   // release the lock afterwards).
-  void AddPlaceholderForPid(base::ProcessHandle pid, int child_process_id);
+  void AddPlaceholderForPid(base::ProcessHandle pid,
+                            int child_process_id,
+                            bool is_gpu_process);
 
   // Implement |ProcessMetrics::PortProvider|.
   mach_port_t TaskForPid(base::ProcessHandle process) const override;
 
   // Implement |BrowserChildProcessObserver|.
   void BrowserChildProcessHostDisconnected(
       const ChildProcessData& data) override;
   void BrowserChildProcessCrashed(const ChildProcessData& data,
       int exit_code) override;
 
@@ skipping 12 matching lines @@
 
   // Updates the mapping for |pid| to include the given |mach_info|.  Does
   // nothing if PlaceholderForPid() has not already been called for the given
   // |pid|.  Callers MUST acquire the lock given by GetLock() before calling
   // this method (and release the lock afterwards).
   void FinalizePid(base::ProcessHandle pid, mach_port_t task_port);
 
   // Removes all mappings belonging to |child_process_id| from the broker.
   void InvalidateChildProcessId(int child_process_id);
 
-  // Returns the Mach port name to use when sending or receiving messages.
-  // Does the Right Thing in the browser and in child processes.
-  static std::string GetMachPortName();
+  // Register an IO surface for use in child process with |client_id|.
+  // Callers MUST acquire the lock given by GetLock() before calling this
+  // method (and release the lock afterwards).
+  bool RegisterIOSurface(base::ProcessHandle pid,

[Daniele Castagna, 2015/05/08 18:58:30]

Are there annotations used in chromium for suggesting that a methods require a
locks?

Something like:
 bool RegisterIOSurface(...) EXCLUSIVE_LOCKS_REQUIRED(lock_);

[reveman, 2015/05/09 15:54:54]

No, that that I know. That'd be nice but I'm afraid the comment will have to do.

+                         int io_surface_id,
+                         int client_id,
+                         mach_port_t io_surface_port);
+
+  // Unregister an IO surface. Callers MUST acquire the lock given by GetLock()
+  // before calling this method (and release the lock afterwards).
+  void UnregisterIOSurface(base::ProcessHandle pid,
+                           int io_surface_id,
+                           int client_id);
+
+  // Acquire IO surface reference for a registered IO surface. This will
+  // only succeed if the IO surface is registered for use in |pid|. Callers
+  // MUST acquire the lock given by GetLock() before calling this method
+  // (and release the lock afterwards).
+  mach_port_t AcquireIOSurface(base::ProcessHandle pid, int io_surface_id);
+
   // Callback used to register notifications on the UI thread.
   void RegisterNotifications();
 
   // True if the listener thread has been started.
   bool listener_thread_started_;
 
   // Used to register for notifications received by NotificationObserver.
   // Accessed only on the UI thread.
   NotificationRegistrar registrar_;
 
   // Stores mach info for every process in the broker.
-  typedef std::map<base::ProcessHandle, mach_port_t> MachMap;
+  struct MachPortSet {
+    MachPortSet();
+    explicit MachPortSet(bool is_gpu_process);
+    ~MachPortSet();
+
+    bool is_gpu_process;
+    mach_port_t task_port;
+    std::map<int, mach_port_t> io_surface_ports;
+  };
+  typedef std::map<base::ProcessHandle, MachPortSet> MachMap;
   MachMap mach_map_;
 
   // Stores the Child process unique id (RenderProcessHost ID) for every
   // process.
   typedef std::map<int, base::ProcessHandle> ChildProcessIdMap;
   ChildProcessIdMap child_process_id_map_;
 
   // Mutex that guards |mach_map_| and |child_process_id_map_|.
   mutable base::Lock lock_;
 
   DISALLOW_COPY_AND_ASSIGN(MachBroker);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MACH_BROKER_MAC_H_