Add support for snapshot loading to Sky

sky/engine/core/script/dart_snapshot_loader.cc

Index: sky/engine/core/script/dart_snapshot_loader.cc
diff --git a/sky/engine/core/script/dart_snapshot_loader.cc b/sky/engine/core/script/dart_snapshot_loader.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fc296b33dd181b3c4a81a1705e4e68e46cad6bfc
--- /dev/null
+++ b/sky/engine/core/script/dart_snapshot_loader.cc
@@ -0,0 +1,66 @@
+// 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/core/script/dart_snapshot_loader.h"
+
+#include "base/callback.h"
+#include "base/trace_event/trace_event.h"
+#include "sky/engine/platform/weborigin/KURL.h"
+#include "sky/engine/tonic/dart_api_scope.h"
+#include "sky/engine/tonic/dart_converter.h"
+#include "sky/engine/tonic/dart_error.h"
+#include "sky/engine/tonic/dart_isolate_scope.h"
+#include "sky/engine/wtf/MainThread.h"
+
+using mojo::common::DataPipeDrainer;
+
+namespace blink {
+
+DartSnapshotLoader::DartSnapshotLoader(DartState* dart_state)
+    : dart_state_(dart_state->GetWeakPtr()) {
+}
+
+DartSnapshotLoader::~DartSnapshotLoader() {
+}
+
+void DartSnapshotLoader::LoadSnapshot(const KURL& url,
+                                      mojo::URLResponsePtr response,
+                                      const base::Closure& callback) {
+  TRACE_EVENT_ASYNC_BEGIN0("sky", "DartSnapshotLoader::LoadSnapshot", this);
+  callback_ = callback;
+
+  if (!response) {
+    fetcher_ = adoptPtr(new MojoFetcher(this, url));
+  } else {
+    OnReceivedResponse(response.Pass());
+  }
+}
+
+void DartSnapshotLoader::OnReceivedResponse(mojo::URLResponsePtr response) {
+  if (response->status_code != 200) {
+    callback_.Run();
+    return;
+  }
+  drainer_ = adoptPtr(new DataPipeDrainer(this, response->body.Pass()));
+}
+
+void DartSnapshotLoader::OnDataAvailable(const void* data, size_t num_bytes) {
+  buffer_.append(static_cast<const uint8_t*>(data), num_bytes);
+}
+
+void DartSnapshotLoader::OnDataComplete() {
+  TRACE_EVENT_ASYNC_END0("sky", "DartSnapshotLoader::LoadSnapshot", this);
+
+  {
+    DartIsolateScope scope(dart_state_->isolate());
+    DartApiScope api_scope;
+
+    LogIfError(Dart_LoadScriptFromSnapshot(buffer_.data(), buffer_.size()));
+  }
+
+  callback_.Run();
+}
+
+}  // namespace blink