Add metrics to help measure effects of installing default apps in a profile.

chrome/browser/ui/webui/ntp/new_tab_page_handler.cc

Index: chrome/browser/ui/webui/ntp/new_tab_page_handler.cc
===================================================================
--- chrome/browser/ui/webui/ntp/new_tab_page_handler.cc	(revision 103269)
+++ chrome/browser/ui/webui/ntp/new_tab_page_handler.cc	(working copy)
@@ -4,6 +4,9 @@
 
 #include "chrome/browser/ui/webui/ntp/new_tab_page_handler.h"
 
+#include "base/metrics/field_trial.h"
+#include "base/metrics/histogram.h"
+#include "chrome/browser/extensions/default_apps_trial.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/sync/profile_sync_service.h"
@@ -15,25 +18,47 @@
 #include "grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util.h"
 
-static const int kIntroDisplayMax = 10;
+namespace {
+const int kIntroDisplayMax = 10;
+}  // anonymous
 
 // The URL of a knowledge-base article about the new NTP.
 static const char kNTP4IntroURL[] =
   "http://www.google.com/support/chrome/bin/answer.py?answer=95451";
 
+WebUIMessageHandler* NewTabPageHandler::Attach(WebUI* web_ui) {
+  // Record an open of the NTP with its default page type.
+  PrefService* prefs = Profile::FromWebUI(web_ui)->GetPrefs();
+  int shown_page_type = prefs->GetInteger(prefs::kNTPShownPage) >>
+      PAGE_ID_OFFSET;
+  UMA_HISTOGRAM_ENUMERATION("NtpHandler.AttachShownPageType",
+                            shown_page_type, 4);
+
+  static bool default_apps_trial_exists =
+      base::FieldTrialList::TrialExists(kDefaultAppsTrial_Name);
+  if (default_apps_trial_exists) {
+    UMA_HISTOGRAM_ENUMERATION(
+        base::FieldTrial::MakeName("NtpHandler.AttachShownPageType",
+                                   kDefaultAppsTrial_Name),
+        shown_page_type, 4);
+  }
+
+  return WebUIMessageHandler::Attach(web_ui);
+}
+
 void NewTabPageHandler::RegisterMessages() {
-  web_ui_->RegisterMessageCallback("closePromo", NewCallback(
+  web_ui()->RegisterMessageCallback("closePromo", NewCallback(
       this, &NewTabPageHandler::HandleClosePromo));
-  web_ui_->RegisterMessageCallback("pageSelected", NewCallback(
+  web_ui()->RegisterMessageCallback("pageSelected", NewCallback(
       this, &NewTabPageHandler::HandlePageSelected));
-  web_ui_->RegisterMessageCallback("introMessageDismissed", NewCallback(
+  web_ui()->RegisterMessageCallback("introMessageDismissed", NewCallback(
       this, &NewTabPageHandler::HandleIntroMessageDismissed));
-  web_ui_->RegisterMessageCallback("introMessageSeen", NewCallback(
+  web_ui()->RegisterMessageCallback("introMessageSeen", NewCallback(
       this, &NewTabPageHandler::HandleIntroMessageSeen));
 }
 
 void NewTabPageHandler::HandleClosePromo(const ListValue* args) {
-  Profile::FromWebUI(web_ui_)->GetPrefs()->SetBoolean(prefs::kNTPPromoClosed,
+  Profile::FromWebUI(web_ui())->GetPrefs()->SetBoolean(prefs::kNTPPromoClosed,
                                                       true);
   NotificationService* service = NotificationService::current();
   service->Notify(chrome::NOTIFICATION_PROMO_RESOURCE_STATE_CHANGED,
@@ -50,17 +75,30 @@
   CHECK(args->GetDouble(1, &index_double));
   int index = static_cast<int>(index_double);
 
-  PrefService* prefs = Profile::FromWebUI(web_ui_)->GetPrefs();
+  PrefService* prefs = Profile::FromWebUI(web_ui())->GetPrefs();
   prefs->SetInteger(prefs::kNTPShownPage, page_id | index);
+
+  int shown_page_type = page_id >> PAGE_ID_OFFSET;
+  UMA_HISTOGRAM_ENUMERATION("NtpHandler.SelectedShownPageType",
+                            shown_page_type, 4);
+
+  static bool default_apps_trial_exists =
+      base::FieldTrialList::TrialExists(kDefaultAppsTrial_Name);
+  if (default_apps_trial_exists) {
+    UMA_HISTOGRAM_ENUMERATION(
+        base::FieldTrial::MakeName("NtpHandler.SelectedShownPageType",
+                                   kDefaultAppsTrial_Name),
+        shown_page_type, 4);
+  }
 }
 
 void NewTabPageHandler::HandleIntroMessageDismissed(const ListValue* args) {
-  PrefService* prefs = Profile::FromWebUI(web_ui_)->GetPrefs();
+  PrefService* prefs = Profile::FromWebUI(web_ui())->GetPrefs();
   prefs->SetInteger(prefs::kNTP4IntroDisplayCount, kIntroDisplayMax + 1);
 }
 
 void NewTabPageHandler::HandleIntroMessageSeen(const ListValue* args) {
-  PrefService* prefs = Profile::FromWebUI(web_ui_)->GetPrefs();
+  PrefService* prefs = Profile::FromWebUI(web_ui())->GetPrefs();
   int intro_displays = prefs->GetInteger(prefs::kNTP4IntroDisplayCount);
   prefs->SetInteger(prefs::kNTP4IntroDisplayCount, intro_displays + 1);
 }