Add option to export tracing events to ETW.

content/app/content_main_runner.cc

Index: content/app/content_main_runner.cc
diff --git a/content/app/content_main_runner.cc b/content/app/content_main_runner.cc
index 43c0d006ccadb7f294366c41e4489e00ba5db2f7..6b19e00f9306a5337f679d7f052a399f60694bb7 100644
--- a/content/app/content_main_runner.cc
+++ b/content/app/content_main_runner.cc
@@ -77,6 +77,7 @@
 #include <cstring>
 
 #include "base/strings/string_number_conversions.h"
+#include "base/trace_event/trace_event_etw_export_win.h"
 #include "ui/base/win/atl_module.h"
 #include "ui/gfx/win/dpi.h"
 #elif defined(OS_MACOSX)
@@ -632,6 +633,12 @@ class ContentMainRunnerImpl : public ContentMainRunner {
           base::trace_event::TraceOptions(
               base::trace_event::RECORD_UNTIL_FULL));
     }
+#if defined(OS_WIN)
+    // Enable exporting of events to ETW if requested on the command line.
+    if (command_line.HasSwitch(switches::kTraceExportEventsToETW))
+      base::trace_event::TraceEventETWExport::EnableETWExport();

[dsinclair, 2015/03/26 18:18:17]

There is more that needs to be done with this switch. It needs to be passed down
to sub processes when they're started. If you search for one of the other
tracing flags you should be able to find where it is also passed.

[Georges Khalil, 2015/03/26 23:09:20]

Done.

+#endif  // OS_WIN
+
 #if !defined(OS_ANDROID)
     // Android tracing started at the beginning of the method.
     // Other OSes have to wait till we get here in order for all the memory