Provide real GPUSupport to ash for Chrome

ash/content_support/gpu_support_impl.h

Index: ash/content_support/gpu_support_impl.h
diff --git a/ash/content_support/gpu_support_impl.h b/ash/content_support/gpu_support_impl.h
index ee82d06d38c24f72cbfa8b421d131cdb89570bb4..7842a291e118c71203bc2ca76d9c0b4d535a2963 100644
--- a/ash/content_support/gpu_support_impl.h
+++ b/ash/content_support/gpu_support_impl.h
@@ -5,11 +5,13 @@
 #ifndef ASH_CONTENT_SUPPORT_GPU_SUPPORT_IMPL_H_
 #define ASH_CONTENT_SUPPORT_GPU_SUPPORT_IMPL_H_
 
+#include "ash/content_support/ash_with_content_export.h"
 #include "ash/gpu_support.h"
 
 namespace ash {
 
-class GPUSupportImpl : public GPUSupport {
+// Support for a real GPU, which relies on access to src/content.
+class ASH_WITH_CONTENT_EXPORT GPUSupportImpl : public GPUSupport {
  public:
   GPUSupportImpl();
   virtual ~GPUSupportImpl();