Reland of Add EnabledStateObserver to BackgroundTracingManager

content/browser/tracing/background_memory_tracing_observer.cc

Index: content/browser/tracing/background_memory_tracing_observer.cc
diff --git a/content/browser/tracing/background_memory_tracing_observer.cc b/content/browser/tracing/background_memory_tracing_observer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..46fa79639439be7ed3f65acca91d8eaf685fda70
--- /dev/null
+++ b/content/browser/tracing/background_memory_tracing_observer.cc
@@ -0,0 +1,35 @@
+// 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 "content/browser/tracing/background_memory_tracing_observer.h"
+
+#include "base/trace_event/memory_dump_manager.h"
+
+namespace content {
+
+// static
+BackgroundMemoryTracingObserver*
+BackgroundMemoryTracingObserver::GetInstance() {
+  static auto* instance = new BackgroundMemoryTracingObserver;
+  return instance;
+}
+
+BackgroundMemoryTracingObserver::BackgroundMemoryTracingObserver() {}
+BackgroundMemoryTracingObserver::~BackgroundMemoryTracingObserver() {}
+
+void BackgroundMemoryTracingObserver::OnScenarioActivated(
+    const BackgroundTracingConfigImpl* config) {}
+
+void BackgroundMemoryTracingObserver::OnTracingEnabled(
+    BackgroundTracingConfigImpl::CategoryPreset preset) {
+  if (preset ==
+      BackgroundTracingConfigImpl::CategoryPreset::BENCHMARK_MEMORY_LIGHT) {
+    auto* dump_manager = base::trace_event::MemoryDumpManager::GetInstance();
+    dump_manager->RequestGlobalDump(
+        base::trace_event::MemoryDumpType::EXPLICITLY_TRIGGERED,
+        base::trace_event::MemoryDumpLevelOfDetail::BACKGROUND);
+  }
+}
+
+}  // namespace content