Enable startup tracing from command line flags in components/tracing

base/trace_event/memory_dump_manager.h

Index: base/trace_event/memory_dump_manager.h
diff --git a/base/trace_event/memory_dump_manager.h b/base/trace_event/memory_dump_manager.h
index 61d1dd085da9c0d027516a5f68b63b4269bf5df4..7579285f84a44da64ad40c115172ec292c0b5c89 100644
--- a/base/trace_event/memory_dump_manager.h
+++ b/base/trace_event/memory_dump_manager.h
@@ -117,6 +117,9 @@ class BASE_EXPORT MemoryDumpManager : public TraceLog::EnabledStateObserver {
   void OnTraceLogEnabled() override;
   void OnTraceLogDisabled() override;
 
+  // Enable heap profiling if kEnableHeapProfiling is specified.
+  void EnableHeapProfilingIfNeeded();
+
   // Returns true if the dump mode is allowed for current tracing session.
   bool IsDumpModeAllowed(MemoryDumpLevelOfDetail dump_mode);
 
@@ -309,9 +312,6 @@ class BASE_EXPORT MemoryDumpManager : public TraceLog::EnabledStateObserver {
   static void FinalizeDumpAndAddToTrace(
       std::unique_ptr<ProcessMemoryDumpAsyncState> pmd_async_state);
 
-  // Enable heap profiling if kEnableHeapProfiling is specified.
-  void EnableHeapProfilingIfNeeded();
-
   // Internal, used only by MemoryDumpManagerDelegate.
   // Creates a memory dump for the current process and appends it to the trace.
   // |callback| will be invoked asynchronously upon completion on the same