Mac: Require child AllocateGpuMemoryBuffer to not fail

content/child/child_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_CHILD_CHILD_IO_SURFACE_MANAGER_MAC_H_
 #define CONTENT_CHILD_CHILD_IO_SURFACE_MANAGER_MAC_H_
 
 #include "base/mac/scoped_mach_port.h"
 #include "base/macros.h"
 #include "base/memory/singleton.h"
 #include "content/common/content_export.h"
 #include "content/common/mac/io_surface_manager_token.h"
 #include "ui/gfx/mac/io_surface_manager.h"
 
 namespace content {
 
 // Implementation of IOSurfaceManager that registers and acquires IOSurfaces
 // through a Mach service.
 class CONTENT_EXPORT ChildIOSurfaceManager : public gfx::IOSurfaceManager {
  public:
   // Returns the global ChildIOSurfaceManager.
   static ChildIOSurfaceManager* GetInstance();
 
   // Overridden from IOSurfaceManager:
   bool RegisterIOSurface(gfx::IOSurfaceId io_surface_id,
                          int client_id,
                          IOSurfaceRef io_surface) override;
   void UnregisterIOSurface(gfx::IOSurfaceId io_surface_id,
                            int client_id) override;
+
+  // This will always return a valid IOSurface (failure will crash).

[reveman, 2015/12/01 20:49:04]

We need to be able to use this in the GPU process without crashing on failure to
solve the problem where GMBs can be become invalid after a gpu process crash.

Is it enough for now to add CHECKs to the user of this interface? If we need
CHECKs here too then let's make it clear that they are only to temporarily
diagnose some crashes by adding TODOs and keeping as much of the existing code
as is.

   IOSurfaceRef AcquireIOSurface(gfx::IOSurfaceId io_surface_id) override;
 
   // Set the service Mach port. Ownership of |service_port| is passed to the
   // manager.
   // Note: This can be called on any thread but must happen before the
   // thread-safe IOSurfaceManager interface is used. It is the responsibility
   // of users of this class to ensure there are no races.
   void set_service_port(mach_port_t service_port) {
     service_port_.reset(service_port);
   }
@@ skipping 14 matching lines @@
 
   base::mac::ScopedMachSendRight service_port_;
   IOSurfaceManagerToken token_;
 
   DISALLOW_COPY_AND_ASSIGN(ChildIOSurfaceManager);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_CHILD_CHILD_IO_SURFACE_MANAGER_MAC_H_