gpu: Add IOSurface backed GpuMemoryBuffer implementation.

content/common/gpu/client/gpu_channel_host.cc

Index: content/common/gpu/client/gpu_channel_host.cc
diff --git a/content/common/gpu/client/gpu_channel_host.cc b/content/common/gpu/client/gpu_channel_host.cc
index 37380cddf3345d280540f00d04a29e85dfc7424e..8b7c55a602f6164688aa2584c6e654b0974dde9b 100644
--- a/content/common/gpu/client/gpu_channel_host.cc
+++ b/content/common/gpu/client/gpu_channel_host.cc
@@ -51,6 +51,9 @@ bool GpuChannelHost::IsValidGpuMemoryBuffer(
     gfx::GpuMemoryBufferHandle handle) {
   switch (handle.type) {
     case gfx::SHARED_MEMORY_BUFFER:
+#if defined(OS_MACOSX)
+    case gfx::IO_SURFACE_BUFFER:
+#endif
       return true;
     default:
       return false;
@@ -306,6 +309,10 @@ gfx::GpuMemoryBufferHandle GpuChannelHost::ShareGpuMemoryBufferToGpuProcess(
       handle.handle = ShareToGpuProcess(source_handle.handle);
       return handle;
     }
+#if defined(OS_MACOSX)
+    case gfx::IO_SURFACE_BUFFER:
+      return source_handle;
+#endif
     default:
       NOTREACHED();
       return gfx::GpuMemoryBufferHandle();