Revert of Move instanced index buffer creation to flush time

include/gpu/GrResourceKey.h

Index: include/gpu/GrResourceKey.h
diff --git a/include/gpu/GrResourceKey.h b/include/gpu/GrResourceKey.h
index 50a71459290574dd107262274aa96dbdcd1db392..aecdc70c0bdcc1b113a1454c018d39fef194aa57 100644
--- a/include/gpu/GrResourceKey.h
+++ b/include/gpu/GrResourceKey.h
@@ -10,7 +10,6 @@
 #define GrResourceKey_DEFINED
 
 #include "GrTypes.h"
-#include "SkOnce.h"
 #include "SkTemplates.h"
 
 uint32_t GrResourceKeyHash(const uint32_t* data, size_t size);
@@ -267,24 +266,6 @@
     };
 };
 
-/**
- * It is common to need a frequently reused GrUniqueKey where the only requirement is that the key
- * is unique. These macros create such a key in a thread safe manner so the key can be truly global
- * and only constructed once.
- */
-
-/** Place outside of function/class definitions. */
-#define GR_DECLARE_STATIC_UNIQUE_KEY(name) SK_DECLARE_STATIC_ONCE(name##_once)
-
-/** Place inside function where the key is used. */
-#define GR_DEFINE_STATIC_UNIQUE_KEY(name)                           \
-    static GrUniqueKey name;                                        \
-    SkOnce(&name##_once, gr_init_static_unique_key_once, &name)
-
-static inline void gr_init_static_unique_key_once(GrUniqueKey* key) {
-    GrUniqueKey::Builder builder(key, GrUniqueKey::GenerateDomain(), 0);
-}
-
 // The cache listens for these messages to purge junk resources proactively.
 class GrUniqueKeyInvalidatedMessage {
 public: