Log some information about the state of the homepage on Android.

chrome/browser/prefs/pref_metrics_service.h

Index: chrome/browser/prefs/pref_metrics_service.h
diff --git a/chrome/browser/prefs/pref_metrics_service.h b/chrome/browser/prefs/pref_metrics_service.h
index 7627e48b4d2f1f8418afe2f7868fd46a7d6860b4..e573501230646351c9822f080f64da8347a41bad 100644
--- a/chrome/browser/prefs/pref_metrics_service.h
+++ b/chrome/browser/prefs/pref_metrics_service.h
@@ -25,6 +25,15 @@ class PrefMetricsService : public KeyedService {
   explicit PrefMetricsService(Profile* profile);
   ~PrefMetricsService() override;
 
+  // Records metrics about the state of the homepage on launch.  On all
+  // platforms except Android this will be triggered automatically as part of
+  // initializing the PrefMetricsService.  On Android, the state of the
+  // homepage is determined by external providers on the device, so this will

[Mark P, 2016/05/24 18:41:53]

"determined by external providers on the device"
is vague.
Perhaps, something like "set by third parties is stored in XYZ (outside of
Chrome)"

[Ted C, 2016/05/24 19:01:33]

Done.

+  // be triggered once all the information can be collected.
+  static void RecordHomePageLaunchMetrics(bool show_home_button,
+                                          bool homepage_is_ntp,
+                                          const GURL& homepage_url);
+
   class Factory : public BrowserContextKeyedServiceFactory {
    public:
     static Factory* GetInstance();