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..174923bf052bc5a88106818d00693d90066ba9a0 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 =
@@ -85,9 +85,15 @@ void OnBrowserStartupComplete() {
   //   cases where Chrome is auto-started and IO is heavily loaded.
   base::TimeDelta startup_time_from_main_entry =
       base::Time::Now() - MainEntryStartTime();
-  UMA_HISTOGRAM_LONG_TIMES(
-      "Startup.BrowserMessageLoopStartTimeFromMainEntry",
-      startup_time_from_main_entry);
+  if (is_first_run) {

[jeremy, 2013/05/06 17:59:38]

Can you make this one call and stick the histogram name in a char* to pass in?

[gab, 2013/05/06 18:44:51]

As explained to me by isherman@ (see [1]): the macros use a static local
variable and thus must have a constant string as their first parameter.

In that CL where we wanted to dynamically add a suffix which led to [2].

Perhaps it would be fine here to have 2 constant strings (i.e. this is not as
bad dynamically generated suffixed strings), but I'm not sure...

[1]
https://chromiumcodereview.appspot.com/14246040/diff/13006/chrome/browser/imp...
[2]
https://chromiumcodereview.appspot.com/14246040/diff/42009/chrome/browser/imp...

[Ilya Sherman, 2013/05/06 23:46:24]

Specifically, the requirement is that string needs to be a runtime constant. 
But, it's simplest not to try to worry about what strings are guaranteed to be
runtime constants vs. not and just do what you've done here.

[gab, 2013/05/07 02:59:03]

I see, thanks for the feedback, will keep it as is.

+    UMA_HISTOGRAM_LONG_TIMES(
+        "Startup.FirstRun.BrowserMessageLoopStartTimeFromMainEntry",

[Ilya Sherman, 2013/05/06 23:46:24]

nit: You might want to name this
"Startup.BrowserMessageLoopStartTimeFromMainEntry.FirstRun" instead, so that the
two histograms are visually grouped on the dashboard (where they get sorted
alphabetically).

[gab, 2013/05/07 02:59:03]

Good point, I initially had more than one Startup.FirstRun stat (see patchset 1)
which is why I originally put it that way (i.e., so that all Startup.FirstRun
stats would be together), but now that it's only one, it will be more
discoverable if it immediately follows the existing stat.

+        startup_time_from_main_entry);
+  } else {
+    UMA_HISTOGRAM_LONG_TIMES(
+        "Startup.BrowserMessageLoopStartTimeFromMainEntry",
+        startup_time_from_main_entry);
+  }
 
   // Create another histogram that records the exact number for use by
   // performance tests.