GPU: Build most of the gpu as a single DLL.

gpu/command_buffer/service/context_group.h

Index: gpu/command_buffer/service/context_group.h
===================================================================
--- gpu/command_buffer/service/context_group.h	(revision 124716)
+++ gpu/command_buffer/service/context_group.h	(working copy)
@@ -14,6 +14,7 @@
 #include "gpu/command_buffer/common/gles2_cmd_format.h"
 #include "gpu/command_buffer/service/gles2_cmd_validation.h"
 #include "gpu/command_buffer/service/feature_info.h"
+#include "gpu/gpu_export.h"
 
 namespace gpu {
 
@@ -32,7 +33,7 @@
 
 // A Context Group helps manage multiple GLES2Decoders that share
 // resources.
-class ContextGroup : public base::RefCounted<ContextGroup> {
+class GPU_EXPORT ContextGroup : public base::RefCounted<ContextGroup> {
  public:
   typedef scoped_refptr<ContextGroup> Ref;