tracing: the recorder implementation

services/resource_coordinator/tracing/recorder.cc

Index: services/resource_coordinator/tracing/recorder.cc
diff --git a/services/resource_coordinator/tracing/recorder.cc b/services/resource_coordinator/tracing/recorder.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fa4f449b0496f83ae61155738c7a7f881bf41178
--- /dev/null
+++ b/services/resource_coordinator/tracing/recorder.cc
@@ -0,0 +1,55 @@
+// Copyright 2017 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 "services/resource_coordinator/tracing/recorder.h"
+
+#include "base/callback_forward.h"
+#include "base/memory/ref_counted.h"
+#include "base/sequenced_task_runner.h"
+#include "services/resource_coordinator/public/interfaces/tracing/tracing.mojom.h"
+
+namespace tracing {
+
+Recorder::Recorder(
+    mojom::RecorderRequest request,
+    bool data_is_array,
+    const base::Closure& on_data_change_callback,
+    const scoped_refptr<base::SequencedTaskRunner>& background_task_runner)
+    : is_recording_(true),
+      data_is_array_(data_is_array),
+      on_data_change_callback_(on_data_change_callback),
+      background_task_runner_(background_task_runner),
+      binding_(this, std::move(request)),
+      weak_factory_(this) {
+  binding_.set_connection_error_handler(base::BindRepeating(
+      &Recorder::OnConnectionError, weak_factory_.GetWeakPtr()));
+}
+
+Recorder::~Recorder() = default;
+
+void Recorder::AddChunk(const std::string& chunk) {
+  if (chunk.empty())
+    return;
+  if (!background_task_runner_->RunsTasksOnCurrentThread()) {
+    background_task_runner_->PostTask(
+        FROM_HERE, base::BindRepeating(&Recorder::AddChunk,
+                                       weak_factory_.GetWeakPtr(), chunk));
+    return;
+  }
+  if (data_is_array_ && !data_.empty())
+    data_.append(",");
+  data_.append(chunk);
+  on_data_change_callback_.Run();
+}
+
+void Recorder::AddMetadata(std::unique_ptr<base::DictionaryValue> metadata) {
+  metadata_.MergeDictionary(metadata.get());
+}
+
+void Recorder::OnConnectionError() {
+  is_recording_ = false;
+  background_task_runner_->PostTask(FROM_HERE, on_data_change_callback_);
+}
+
+}  // namespace tracing