Show registered native allocations in ahat.

Bug: 23130675
Change-Id: I1d7f41a47a956b30611429b9bd395ec5f9580209
diff --git a/tools/ahat/src/OverviewHandler.java b/tools/ahat/src/OverviewHandler.java
index 720fcb4..0dbad7e 100644
--- a/tools/ahat/src/OverviewHandler.java
+++ b/tools/ahat/src/OverviewHandler.java
@@ -48,6 +48,22 @@
 
     doc.section("Heap Sizes");
     printHeapSizes(doc, query);
+
+    List<InstanceUtils.NativeAllocation> allocs = mSnapshot.getNativeAllocations();
+    if (!allocs.isEmpty()) {
+      doc.section("Registered Native Allocations");
+      long totalSize = 0;
+      for (InstanceUtils.NativeAllocation alloc : allocs) {
+        totalSize += alloc.size;
+      }
+      doc.descriptions();
+      doc.description(DocString.text("Number of Registered Native Allocations"),
+          DocString.format("%,14d", allocs.size()));
+      doc.description(DocString.text("Total Size of Registered Native Allocations"),
+          DocString.format("%,14d", totalSize));
+      doc.end();
+    }
+
     doc.big(Menu.getMenu());
   }