Update monet.

tools/clang/blink_gc_plugin/CheckGCRootsVisitor.cpp

Index: tools/clang/blink_gc_plugin/CheckGCRootsVisitor.cpp
diff --git a/tools/clang/blink_gc_plugin/CheckGCRootsVisitor.cpp b/tools/clang/blink_gc_plugin/CheckGCRootsVisitor.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..ab2d2601bc3e527a39e144b1b0d6ccb022a4f7de
--- /dev/null
+++ b/tools/clang/blink_gc_plugin/CheckGCRootsVisitor.cpp
@@ -0,0 +1,53 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "CheckGCRootsVisitor.h"
+
+CheckGCRootsVisitor::CheckGCRootsVisitor() {
+}
+
+CheckGCRootsVisitor::Errors& CheckGCRootsVisitor::gc_roots() {
+  return gc_roots_;
+}
+
+bool CheckGCRootsVisitor::ContainsGCRoots(RecordInfo* info) {
+  for (RecordInfo::Fields::iterator it = info->GetFields().begin();
+       it != info->GetFields().end();
+       ++it) {
+    current_.push_back(&it->second);
+    it->second.edge()->Accept(this);
+    current_.pop_back();
+  }
+  return !gc_roots_.empty();
+}
+
+void CheckGCRootsVisitor::VisitValue(Value* edge) {
+  // TODO: what should we do to check unions?
+  if (edge->value()->record()->isUnion())
+    return;
+
+  // Prevent infinite regress for cyclic part objects.
+  if (visiting_set_.find(edge->value()) != visiting_set_.end())
+    return;
+
+  visiting_set_.insert(edge->value());
+  // If the value is a part object, then continue checking for roots.
+  for (Context::iterator it = context().begin();
+       it != context().end();
+       ++it) {
+    if (!(*it)->IsCollection())
+      return;
+  }
+  ContainsGCRoots(edge->value());
+  visiting_set_.erase(edge->value());
+}
+
+void CheckGCRootsVisitor::VisitPersistent(Persistent* edge) {
+  gc_roots_.push_back(current_);
+}
+
+void CheckGCRootsVisitor::AtCollection(Collection* edge) {
+  if (edge->is_root())
+    gc_roots_.push_back(current_);
+}