Replace IOSurfaceManager by directly passing IOSurface Mach ports over Chrome IPC.

ui/gfx/gpu_memory_buffer.h

Index: ui/gfx/gpu_memory_buffer.h
diff --git a/ui/gfx/gpu_memory_buffer.h b/ui/gfx/gpu_memory_buffer.h
index 47d277ea64dced60192ee7dc3414118fc0f75384..837caf69a8722479eba5a8e556a09432f75ddd84 100644
--- a/ui/gfx/gpu_memory_buffer.h
+++ b/ui/gfx/gpu_memory_buffer.h
@@ -15,6 +15,8 @@
 
 #if defined(USE_OZONE)
 #include "ui/gfx/native_pixmap_handle_ozone.h"
+#elif defined(OS_MACOSX)
+#include "base/mac/scoped_mach_port.h"
 #endif
 
 extern "C" typedef struct _ClientBuffer* ClientBuffer;
@@ -34,6 +36,7 @@ using GpuMemoryBufferId = GenericSharedMemoryId;
 
 struct GFX_EXPORT GpuMemoryBufferHandle {
   GpuMemoryBufferHandle();
+  ~GpuMemoryBufferHandle();
   bool is_null() const { return type == EMPTY_BUFFER; }
   GpuMemoryBufferType type;
   GpuMemoryBufferId id;
@@ -42,6 +45,8 @@ struct GFX_EXPORT GpuMemoryBufferHandle {
   int32_t stride;
 #if defined(USE_OZONE)
   NativePixmapHandle native_pixmap_handle;
+#elif defined(OS_MACOSX)
+  base::mac::ScopedRefCountedMachSendRight mach_port;

[ccameron, 2015/12/21 19:30:14]

The existence of this port will result in the IOSurface being seen as "in use"
for as long as any GpuMemoryBufferHandle to that IOSurface exists in any
process.

This appears to be okay, but we will need to be careful to not hold
GpuMemoryBufferHandles around any longer than they are needed (e.g, if the
renderer which owns a GMB were to cache a handle to it, the result would be that
it would always look that the GMB were in use by the system).

 #endif
 };