make SkRefCnt::getRefCnt() debug-only, remove it from SkNVRefCnt.

tests/MetaDataTest.cpp

Index: tests/MetaDataTest.cpp
diff --git a/tests/MetaDataTest.cpp b/tests/MetaDataTest.cpp
index eb7eae9e0f5eb6dfe0a5e15b57f698c59aadb556..8ed1e493ec18ed3ba31e42c2964d85c837034e4f 100644
--- a/tests/MetaDataTest.cpp
+++ b/tests/MetaDataTest.cpp
@@ -10,7 +10,7 @@
 
 static void test_ptrs(skiatest::Reporter* reporter) {
     SkRefCnt ref;
-    REPORTER_ASSERT(reporter, 1 == ref.getRefCnt());
+    REPORTER_ASSERT(reporter, ref.unique());
 
     {
         SkMetaData md0, md1;
@@ -19,19 +19,19 @@ static void test_ptrs(skiatest::Reporter* reporter) {
         md0.setRefCnt(name, &ref);
         REPORTER_ASSERT(reporter, md0.findRefCnt(name));
         REPORTER_ASSERT(reporter, md0.hasRefCnt(name, &ref));
-        REPORTER_ASSERT(reporter, 2 == ref.getRefCnt());
+        REPORTER_ASSERT(reporter, !ref.unique());
 
         md1 = md0;
         REPORTER_ASSERT(reporter, md1.findRefCnt(name));
         REPORTER_ASSERT(reporter, md1.hasRefCnt(name, &ref));
-        REPORTER_ASSERT(reporter, 3 == ref.getRefCnt());
+        REPORTER_ASSERT(reporter, !ref.unique());
 
         REPORTER_ASSERT(reporter, md0.removeRefCnt(name));
         REPORTER_ASSERT(reporter, !md0.findRefCnt(name));
         REPORTER_ASSERT(reporter, !md0.hasRefCnt(name, &ref));
-        REPORTER_ASSERT(reporter, 2 == ref.getRefCnt());
+        REPORTER_ASSERT(reporter, !ref.unique());
     }
-    REPORTER_ASSERT(reporter, 1 == ref.getRefCnt());
+    REPORTER_ASSERT(reporter, ref.unique());
 }
 
 DEF_TEST(MetaData, reporter) {