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

chrome/browser/prefs/pref_metrics_service.cc

Index: chrome/browser/prefs/pref_metrics_service.cc
diff --git a/chrome/browser/prefs/pref_metrics_service.cc b/chrome/browser/prefs/pref_metrics_service.cc
index 54ee8505c59947eac378c7a6405f4ee6d2532bc2..f3685ba6d4d3340196c01583b5fdc087752ab53e 100644
--- a/chrome/browser/prefs/pref_metrics_service.cc
+++ b/chrome/browser/prefs/pref_metrics_service.cc
@@ -78,13 +78,14 @@ PrefMetricsService::PrefMetricsService(Profile* profile,
 PrefMetricsService::~PrefMetricsService() {
 }
 
-void PrefMetricsService::RecordLaunchPrefs() {
-  bool show_home_button = prefs_->GetBoolean(prefs::kShowHomeButton);
-  bool home_page_is_ntp = prefs_->GetBoolean(prefs::kHomePageIsNewTabPage);
+// static
+void PrefMetricsService::RecordHomePageLaunchMetrics(bool show_home_button,
+                                                     bool homepage_is_ntp,
+                                                     const GURL& homepage_url) {
   UMA_HISTOGRAM_BOOLEAN("Settings.ShowHomeButton", show_home_button);
   if (show_home_button) {
     UMA_HISTOGRAM_BOOLEAN("Settings.GivenShowHomeButton_HomePageIsNewTabPage",
-                          home_page_is_ntp);
+                          homepage_is_ntp);
   }
 
   // For non-NTP homepages, see if the URL comes from the same TLD+1 as a known
@@ -94,8 +95,7 @@ void PrefMetricsService::RecordLaunchPrefs() {
   // (pages that share a TLD+1 with a known engine but aren't actually search
   // pages, e.g. plus.google.com).  Additionally, record the TLD+1 of non-NTP
   // homepages through the privacy-preserving Rappor service.
-  if (!home_page_is_ntp) {
-    GURL homepage_url(prefs_->GetString(prefs::kHomePage));
+  if (!homepage_is_ntp) {
     if (homepage_url.is_valid()) {
       UMA_HISTOGRAM_ENUMERATION(
           "Settings.HomePageEngineType",
@@ -106,6 +106,15 @@ void PrefMetricsService::RecordLaunchPrefs() {
           homepage_url);
     }
   }
+}
+
+void PrefMetricsService::RecordLaunchPrefs() {
+#if !defined(OS_ANDROID)

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

Please comment here why we skip it on Android (by restating the reason that you
put in the .h file and also referencing where the code in Android that calls
RecordHomePageLaunchMetrics is).

[Ted C, 2016/05/24 19:01:32]

Done.

+  GURL homepage_url(prefs_->GetString(prefs::kHomePage));
+  RecordHomePageLaunchMetrics(prefs_->GetBoolean(prefs::kShowHomeButton),
+                              prefs_->GetBoolean(prefs::kHomePageIsNewTabPage),
+                              homepage_url);
+#endif
 
   SampleNewTabPageURL(profile_);

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

Given your answers to the comments on the earlier patchset, I think you should
ifdef this out (and comment why).

ditto for ifdefing out the startup settings (and comment)

and while you're here, please comment why the pinned tabs is ifdefed out on
Android.  I assume
// Android does not support pinned tabs.

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

Done.