Add support for the ExperimentalSwReporterEngine field trial.

chrome/browser/safe_browsing/srt_fetcher_win.h

Index: chrome/browser/safe_browsing/srt_fetcher_win.h
diff --git a/chrome/browser/safe_browsing/srt_fetcher_win.h b/chrome/browser/safe_browsing/srt_fetcher_win.h
index 6339a001345400ee5d80d764069d565d4c82843d..d1a8872065e341e299c68b63a7a290a21a97e675 100644
--- a/chrome/browser/safe_browsing/srt_fetcher_win.h
+++ b/chrome/browser/safe_browsing/srt_fetcher_win.h
@@ -45,6 +45,15 @@ const int kDaysBetweenSwReporterRunsForPendingPrompt = 1;
 struct SwReporterInvocation {
   base::CommandLine command_line;
 
+  // Experimental versions of the reporter will write metrics to registry keys
+  // ending in |suffix|. Those metrics should be copied to UMA histograms also
+  // ending in |suffix|. For the canonical version, |suffix| will be empty.
+  std::string suffix;
+
+  // The experimental sw_reporter never triggers the prompt, just reports
+  // results through UMA.
+  bool is_experimental = false;

[csharp, 2016/08/25 22:28:14]

Could you add an bool for show_prompt? Gating prompting on the is_experimental
flag just seems a bit odd

[Joe Mason, 2016/08/25 23:17:00]

I change this to a feature flag in the next patch when I add more uses.

+
   SwReporterInvocation();
 
   static SwReporterInvocation FromFilePath(const base::FilePath& exe_path);