Add the c++ code part of bindings2/

sky/engine/bindings2/dart_event_listener.cc

Index: sky/engine/bindings2/dart_event_listener.cc
diff --git a/sky/engine/bindings2/dart_event_listener.cc b/sky/engine/bindings2/dart_event_listener.cc
new file mode 100644
index 0000000000000000000000000000000000000000..70e1b2aa1c7a3fae23b8e475a77b5519142c092e
--- /dev/null
+++ b/sky/engine/bindings2/dart_event_listener.cc
@@ -0,0 +1,69 @@
+// 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 "sky/engine/config.h"
+#include "sky/engine/bindings2/dart_event_listener.h"
+
+#include "sky/engine/core/events/Event.h"
+#include "sky/engine/tonic/dart_api_scope.h"
+#include "sky/engine/tonic/dart_error.h"
+#include "sky/engine/tonic/dart_gc_visitor.h"
+#include "sky/engine/tonic/dart_isolate_scope.h"
+
+namespace blink {
+
+PassRefPtr<DartEventListener> DartEventListener::FromDart(Dart_Handle handle) {
+  if (!Dart_IsClosure(handle))
+    return nullptr;
+  void* peer = nullptr;
+  CHECK(!Dart_IsError(Dart_GetPeer(handle, &peer)));

[eseidel, 2015/02/12 21:09:37]

It's a bit strange to have GetPeer inside this CHECK.  I would split it out.

+  if (DartEventListener* listener = static_cast<DartEventListener*>(peer))

[eseidel, 2015/02/12 21:09:37]

Should we just have toDartEventHandler(handle)?

+    return listener;
+  RefPtr<DartEventListener> listener = adoptRef(new DartEventListener(handle));
+  listener->data_state_ = DartState::Current()->GetWeakPtr();
+  DCHECK(Dart_IsClosure(handle));
+  listener->ref();  // Balanced in Finalize
+  listener->closure_ = Dart_NewPrologueWeakPersistentHandle(
+      handle, listener.get(), sizeof(*listener), &DartEventListener::Finalize);
+  CHECK(!Dart_IsError(Dart_SetPeer(handle, listener.get())));
+  return listener.release();
+}
+
+DartEventListener::DartEventListener(Dart_Handle handle) : closure_(nullptr) {
+}
+
+DartEventListener::~DartEventListener() {
+}
+
+void DartEventListener::handleEvent(ExecutionContext* context, Event* event) {
+  if (!closure_ || !data_state_)
+    return;
+
+  DartIsolateScope scope(data_state_->isolate());
+  DartApiScope api_scope;
+
+  // Notice that we protect ourselves as well as the closure object in the VM.
+  RefPtr<DartEventListener> protect(this);
+  Dart_Handle closure_handle = Dart_HandleFromWeakPersistent(closure_);
+  Dart_Handle event_handle = ToDart(event);
+  DCHECK(event_handle);
+
+  Dart_Handle params[] = {event_handle};
+  LogIfError(Dart_InvokeClosure(closure_handle, arraysize(params), params));
+}
+
+void DartEventListener::AcceptDartGCVisitor(DartGCVisitor& visitor) const {
+  CHECK(!Dart_IsError(Dart_AppendValueToWeakReferenceSet(
+      visitor.current_set(), closure_)));
+}
+
+void DartEventListener::Finalize(void* isolate_callback_data,
+                                 Dart_WeakPersistentHandle handle,
+                                 void* peer) {
+  DartEventListener* listener = static_cast<DartEventListener*>(peer);
+  listener->closure_ = nullptr;
+  listener->deref();  // Balances ref in DartEventListener::DartEventListener
+}
+
+}  // namespace blink