Move Mailbox from cc to gpu, and its traits to gpu/ipc

cc/transferable_resource.h

Index: cc/transferable_resource.h
diff --git a/cc/transferable_resource.h b/cc/transferable_resource.h
index 8833ff57dc3d7575306aa48c10cd60699d0b3bed..0c9bfa27b9605b32a7129224788d1002b3fe62c1 100644
--- a/cc/transferable_resource.h
+++ b/cc/transferable_resource.h
@@ -9,17 +9,11 @@
 
 #include "base/basictypes.h"
 #include "cc/cc_export.h"
+#include "gpu/command_buffer/common/mailbox.h"
 #include "ui/gfx/size.h"
 
 namespace cc {
 
-struct CC_EXPORT Mailbox {
-  Mailbox();
-  bool isZero() const;
-  void setName(const int8* name);
-  int8 name[64];
-};
-
 struct CC_EXPORT TransferableResource {
   TransferableResource();
   ~TransferableResource();
@@ -29,7 +23,7 @@ struct CC_EXPORT TransferableResource {
   uint32 format;
   uint32 filter;
   gfx::Size size;
-  Mailbox mailbox;
+  gpu::Mailbox mailbox;
 };
 
 typedef std::vector<TransferableResource> TransferableResourceArray;