ART: Add heap iteration callback

Add callback support for heap iteration. Visiting of fields will
be done in a follow-up.

Add a test.

Bug: 31385354
Test: m test-art-host-run-test-906-iterate-heap
Test: m ART_TEST_GC_STRESS=true ART_TEST_GC_VERIFY=true test-art-host-run-test-906-iterate-heap
Change-Id: I7bcf6751e6df4ef58756ba97701050b2ff5eb07b
diff --git a/runtime/openjdkjvmti/heap.h b/runtime/openjdkjvmti/heap.h
new file mode 100644
index 0000000..fb9a216
--- /dev/null
+++ b/runtime/openjdkjvmti/heap.h
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_RUNTIME_OPENJDKJVMTI_HEAP_H_
+#define ART_RUNTIME_OPENJDKJVMTI_HEAP_H_
+
+#include "jvmti.h"
+
+namespace openjdkjvmti {
+
+class ObjectTagTable;
+
+class HeapUtil {
+ public:
+  explicit HeapUtil(ObjectTagTable* tags) : tags_(tags) {
+  }
+
+  jvmtiError IterateThroughHeap(jvmtiEnv* env,
+                                jint heap_filter,
+                                jclass klass,
+                                const jvmtiHeapCallbacks* callbacks,
+                                const void* user_data);
+
+  ObjectTagTable* GetTags() {
+    return tags_;
+  }
+
+ private:
+  ObjectTagTable* tags_;
+};
+
+}  // namespace openjdkjvmti
+
+#endif  // ART_RUNTIME_OPENJDKJVMTI_HEAP_H_