Record first run startup metrics.

chrome/common/startup_metric_utils.cc

Index: chrome/common/startup_metric_utils.cc
diff --git a/chrome/common/startup_metric_utils.cc b/chrome/common/startup_metric_utils.cc
index 6b12be5f51ab7b5d877371f54d9573abb491ace8..fbc80f850fada21b4fea786f4d12930a66fa1216 100644
--- a/chrome/common/startup_metric_utils.cc
+++ b/chrome/common/startup_metric_utils.cc
@@ -65,7 +65,7 @@ const base::Time MainEntryStartTime() {
   return *MainEntryPointTimeInternal();
 }
 
-void OnBrowserStartupComplete() {
+void OnBrowserStartupComplete(bool is_first_run) {
   // Bail if uptime < 7 minutes, to filter out cases where Chrome may have been
   // autostarted and the machine is under io pressure.
   const int64 kSevenMinutesInMilliseconds =
@@ -86,7 +86,9 @@ void OnBrowserStartupComplete() {
   base::TimeDelta startup_time_from_main_entry =
       base::Time::Now() - MainEntryStartTime();
   UMA_HISTOGRAM_LONG_TIMES(
-      "Startup.BrowserMessageLoopStartTimeFromMainEntry",
+      is_first_run ?
+          "Startup.FirstRun.BrowserMessageLoopStartTimeFromMainEntry" :
+          "Startup.BrowserMessageLoopStartTimeFromMainEntry",

[gab, 2013/05/06 16:19:54]

Also split this into two explicit calls since these macros are meant to be used
with constant histogram values I think.

       startup_time_from_main_entry);
 
   // Create another histogram that records the exact number for use by
@@ -94,7 +96,9 @@ void OnBrowserStartupComplete() {
   int64 startup_time_from_main_entry_ms =
       startup_time_from_main_entry.InMilliseconds();
   HISTOGRAM_ENUMERATION(
-      "Startup.BrowserMessageLoopStartTimeFromMainEntry_Exact",
+      is_first_run ?
+          "Startup.FirstRun.BrowserMessageLoopStartTimeFromMainEntry_Exact" :

[jeremy, 2013/05/05 12:35:56]

This histogram is only used for perf tests and is never sent to the server - I
don't think we need to add a new variant for first run...

[gab, 2013/05/06 16:19:54]

Done.

+          "Startup.BrowserMessageLoopStartTimeFromMainEntry_Exact",
       startup_time_from_main_entry_ms,
       startup_time_from_main_entry_ms);