Set up background memory light tracing field trials

content/browser/tracing/background_tracing_manager_impl.h

 // 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.
 
 #ifndef CONTENT_BROWSER_TRACING_BACKGROUND_TRACING_MANAGER_IMPL_H_
 #define CONTENT_BROWSER_TRACING_BACKGROUND_TRACING_MANAGER_IMPL_H_
 
 #include <memory>
 
 #include "base/lazy_instance.h"
@@ skipping 36 matching lines @@
       const base::Closure& callback) override;
   CONTENT_EXPORT void SetRuleTriggeredCallbackForTesting(
       const base::Closure& callback);
   void FireTimerForTesting() override;
   CONTENT_EXPORT bool IsTracingForTesting();
 
  private:
   BackgroundTracingManagerImpl();
   ~BackgroundTracingManagerImpl() override;
 
-  void StartTracing(std::string, base::trace_event::TraceRecordMode);
+  void StartTracing(BackgroundTracingConfigImpl::CategoryPreset,
+                    base::trace_event::TraceRecordMode);
   void StartTracingIfConfigNeedsIt();
   void OnFinalizeStarted(std::unique_ptr<const base::DictionaryValue> metadata,
                          base::RefCountedString*);
   void OnFinalizeComplete();
   void BeginFinalizing(StartedFinalizingCallback);
   void ValidateStartupScenario();
 
   void AddCustomMetadata(TracingControllerImpl::TraceDataSink*) const;
 
   std::string GetTriggerNameFromHandle(TriggerHandle handle) const;
@@ skipping 40 matching lines @@
   base::Closure rule_triggered_callback_for_testing_;
 
   friend struct base::DefaultLazyInstanceTraits<BackgroundTracingManagerImpl>;
 
   DISALLOW_COPY_AND_ASSIGN(BackgroundTracingManagerImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_TRACING_BACKGROUND_TRACING_MANAGER_IMPL_H_