Re-land first pass BackgroundTracingManager.

content/browser/tracing/background_tracing_scenario.cc

+// Copyright (c) 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 "content/browser/tracing/background_tracing_scenario.h"
+
+#include "content/browser/tracing/background_tracing_endpoint.h"
+#include "content/browser/tracing/background_tracing_manager.h"
+#include "content/public/browser/browser_thread.h"
+
+BackgroundTracingScenario::BackgroundTracingScenario(
+    scoped_refptr<BackgroundTracingEndpoint> endpoint) {
+  endpoint_ = endpoint;
+}
+
+BackgroundTracingScenario::~BackgroundTracingScenario() {
+}
+
+scoped_refptr<BackgroundTracingEndpoint>
+BackgroundTracingScenario::GetEndpoint() {
+  return endpoint_;
+}
+
+base::trace_event::CategoryFilter BackgroundTracingScenario::GetCategoryFilter()

[oystein (OOO til 10th of July), 2015/04/21 17:31:44]

nit: maybe  base::trace_event::CategoryFilter on a separate line instead.

+    const {
+  return base::trace_event::CategoryFilter(
+      "benchmark,disabled-by-default-toplevel.flow,"
+      "disabled-by-default-ipc.flow");
+}