zero-copy: Clarify to allocate/destroy GpuMemoryBuffer on any thread and use it on the main thread o

ui/ozone/gpu/gpu_memory_buffer_factory_ozone_native_buffer.cc

Index: ui/ozone/gpu/gpu_memory_buffer_factory_ozone_native_buffer.cc
diff --git a/ui/ozone/gpu/gpu_memory_buffer_factory_ozone_native_buffer.cc b/ui/ozone/gpu/gpu_memory_buffer_factory_ozone_native_buffer.cc
index 38667e51e180f2d306fc50ec87e8994da9d88e1f..fe30e17ed0c09140f7d5b7798835631070f35311 100644
--- a/ui/ozone/gpu/gpu_memory_buffer_factory_ozone_native_buffer.cc
+++ b/ui/ozone/gpu/gpu_memory_buffer_factory_ozone_native_buffer.cc
@@ -166,7 +166,8 @@ GpuMemoryBufferFactoryOzoneNativeBuffer::CreateImageForGpuMemoryBuffer(
     gfx::GpuMemoryBuffer::Format format,
     unsigned internalformat,
     int client_id) {
-  NativePixmap* pixmap = nullptr;
+  DCHECK(thread_checker_.CalledOnValidThread());

[reveman, 2015/04/07 13:07:05]

ditto

[dshwang, 2015/04/07 14:04:26]

ditto

+  scoped_refptr<NativePixmap> pixmap(nullptr);

[reveman, 2015/04/07 13:07:05]

what's wrong with the previous code?

[dshwang, 2015/04/07 14:04:26]

nothing wrong. I'll roll back

   {
     base::AutoLock lock(native_pixmap_map_lock_);
     BufferToPixmapMap::iterator it =
@@ -174,7 +175,7 @@ GpuMemoryBufferFactoryOzoneNativeBuffer::CreateImageForGpuMemoryBuffer(
     if (it == native_pixmap_map_.end()) {
       return scoped_refptr<gfx::GLImage>();
     }
-    pixmap = it->second.get();
+    pixmap.swap(it->second);
   }
   return CreateImageForPixmap(pixmap, size, format, internalformat);
 }