ART: Add Heap JVMTI extension API

Add extension API for Android heaps. Add a function that returns
the heap id for a tag (implying an object). Add a function that
returns the heap name for a given heap id.

Add tests.

Bug: 37283268
Test: m test-art-host
Test: art/test/testrunner/testrunner.py -b --host -t 913
Test: cts-tradefed run cts-dev --module CtsJvmtiRunTest913HostTestCases
Change-Id: I3a140ce00a33507c9ac3263d0badd10f3daf558c
diff --git a/runtime/openjdkjvmti/jvmti_weak_table-inl.h b/runtime/openjdkjvmti/jvmti_weak_table-inl.h
index f67fffc..64ab3e7 100644
--- a/runtime/openjdkjvmti/jvmti_weak_table-inl.h
+++ b/runtime/openjdkjvmti/jvmti_weak_table-inl.h
@@ -384,6 +384,23 @@
   return ERR(NONE);
 }
 
+template <typename T>
+art::mirror::Object* JvmtiWeakTable<T>::Find(T tag) {
+  art::Thread* self = art::Thread::Current();
+  art::MutexLock mu(self, allow_disallow_lock_);
+  Wait(self);
+
+  for (auto& pair : tagged_objects_) {
+    if (tag == pair.second) {
+      art::mirror::Object* obj = pair.first.template Read<art::kWithReadBarrier>();
+      if (obj != nullptr) {
+        return obj;
+      }
+    }
+  }
+  return nullptr;
+}
+
 }  // namespace openjdkjvmti
 
 #endif  // ART_RUNTIME_OPENJDKJVMTI_JVMTI_WEAK_TABLE_INL_H_