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

chrome/browser/prefs/pref_metrics_service.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/prefs/pref_metrics_service.h"
 
 #include <stddef.h>
 
 #include "base/bind.h"
 #include "base/command_line.h"
@@ skipping 60 matching lines @@
                                        PrefService* local_state)
     : profile_(profile),
       prefs_(profile->GetPrefs()),
       local_state_(local_state),
       weak_factory_(this) {
 }
 
 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
   // search engine.  Note that this is only an approximation of search engine
   // use, due to both false negatives (pages that come from unknown TLD+1 X but
   // consist of a search box that sends to known TLD+1 Y) and false positives
   // (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",
           TemplateURLPrepopulateData::GetEngineType(homepage_url),
           SEARCH_ENGINE_MAX);
       rappor::SampleDomainAndRegistryFromGURL(
           g_browser_process->rappor_service(), "Settings.HomePage2",
           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.

 
   int restore_on_startup = prefs_->GetInteger(prefs::kRestoreOnStartup);
   UMA_HISTOGRAM_ENUMERATION("Settings.StartupPageLoadSettings",
                             restore_on_startup, kSessionStartupPrefValueMax);
   if (restore_on_startup == SessionStartupPref::kPrefValueURLs) {
     const base::ListValue* url_list =
         prefs_->GetList(prefs::kURLsToRestoreOnStartup);
     UMA_HISTOGRAM_CUSTOM_COUNTS("Settings.StartupPageLoadURLs",
                                 url_list->GetSize(), 1, 50, 20);
     // Similarly, check startup pages for known search engine TLD+1s.
@@ skipping 128 matching lines @@
 }
 
 bool PrefMetricsService::Factory::ServiceIsNULLWhileTesting() const {
   return false;
 }
 
 content::BrowserContext* PrefMetricsService::Factory::GetBrowserContextToUse(
     content::BrowserContext* context) const {
   return chrome::GetBrowserContextRedirectedInIncognito(context);
 }