Revert of make getContentKey() available in GrGpuResource public interface

src/gpu/GrResourceCache2.h

Index: src/gpu/GrResourceCache2.h
diff --git a/src/gpu/GrResourceCache2.h b/src/gpu/GrResourceCache2.h
index 9c9900a42400bfd1d3fa3f2ab0b76de4fed588cb..d5c418238ba480e9bc3017547b144075520b3b9c 100644
--- a/src/gpu/GrResourceCache2.h
+++ b/src/gpu/GrResourceCache2.h
@@ -194,7 +194,7 @@
 
     struct ContentHashTraits {
         static const GrContentKey& GetKey(const GrGpuResource& r) {
-            return r.getContentKey();
+            return r.cacheAccess().getContentKey();
         }
 
         static uint32_t Hash(const GrContentKey& key) { return key.hash(); }