Convert components/tracing from static lib to component

components/tracing/startup_tracing.h

Index: components/tracing/startup_tracing.h
diff --git a/components/tracing/startup_tracing.h b/components/tracing/startup_tracing.h
index ae68f6fa654e17736c7ffef9126a2aa8d2ab9911..5d1c74d05c19e1f222b1fe844ec57bf60b15f5a2 100644
--- a/components/tracing/startup_tracing.h
+++ b/components/tracing/startup_tracing.h
@@ -5,13 +5,15 @@
 #ifndef COMPONENTS_TRACING_STARTUP_TRACING_H_
 #define COMPONENTS_TRACING_STARTUP_TRACING_H_
 
+#include "components/tracing/tracing_export.h"
+
 namespace tracing {
 
 // Enable startup tracing according to the trace config file. If the trace
 // config file does not exist, it will do nothing. This is designed to be used
 // by Telemetry. Telemetry will stop tracing via DevTools later. To avoid
 // conflict, this should not be used when --trace-startup is enabled.
-void EnableStartupTracingIfConfigFileExists();
+void TRACING_EXPORT EnableStartupTracingIfConfigFileExists();
 
 }  // namespace tracing