Re-land first pass BackgroundTracingManager.

content/public/browser/background_tracing_reactive_config.cc

Index: content/public/browser/background_tracing_reactive_config.cc
diff --git a/content/public/browser/background_tracing_reactive_config.cc b/content/public/browser/background_tracing_reactive_config.cc
new file mode 100644
index 0000000000000000000000000000000000000000..03e2ea26852b5623be07be558954a42b596a8c9d
--- /dev/null
+++ b/content/public/browser/background_tracing_reactive_config.cc
@@ -0,0 +1,16 @@
+// 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 "content/public/browser/background_tracing_reactive_config.h"
+
+namespace content {
+
+BackgroundTracingReactiveConfig::BackgroundTracingReactiveConfig()
+    : BackgroundTracingConfig(BackgroundTracingConfig::REACTIVE_TRACING_MODE) {
+}
+
+BackgroundTracingReactiveConfig::~BackgroundTracingReactiveConfig() {
+}
+
+}  // namespace content