Use GrResourceCache2 to service content key lookups

src/core/SkTMultiMap.h

Index: src/core/SkTMultiMap.h
diff --git a/src/core/SkTMultiMap.h b/src/core/SkTMultiMap.h
index 70076f0cad2d0dc1b2cd0ab7f5df28116916a16b..1168ed6e915a0cd7d0c05144eaa1f1c24516c336 100644
--- a/src/core/SkTMultiMap.h
+++ b/src/core/SkTMultiMap.h
@@ -102,6 +102,19 @@ public:
 
     int count() const { return fCount; }
 
+#ifdef SK_DEBUG
+    // This is not particularly fast and only used for validation, so debug only.
+    int countForKey(const Key& key) const {
+        int count = 0;
+        ValueList* list = fHash.find(key);
+        while (list) {
+            list = list->fNext;
+            ++count;
+        }
+        return count;
+    }
+#endif
+
 private:
     SkTDynamicHash<ValueList, Key> fHash;
     int fCount;