cros: Default pinned apps experiment.

- Setup default pinned apps field trial when a regular
  user signs in;
- Existing user prior the trial goes to "Existing" group;
- New users split 50/50 to "Control" and "Alternate";
- "Alternate" group users get the alternate default pinned
  apps;
- Add click UMA histogram to compare clicks on the shelf;

BUG=234415

Review URL: https://chromiumcodereview.appspot.com/14566003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@198327 0039d316-1c4b-4281-b951-d872f2087c98

19 files changed, 478 insertions, 44 deletions

diff --git a/chrome/browser/chromeos/chrome_browser_main_chromeos.cc b/chrome/browser/chromeos/chrome_browser_main_chromeos.cc
index 4662315..a54caae 100644
--- a/chrome/browser/chromeos/chrome_browser_main_chromeos.cc
+++ b/chrome/browser/chromeos/chrome_browser_main_chromeos.cc
@@ -44,6 +44,7 @@
 #include "chrome/browser/chromeos/kiosk_mode/kiosk_mode_screensaver.h"
 #include "chrome/browser/chromeos/kiosk_mode/kiosk_mode_settings.h"
 #include "chrome/browser/chromeos/login/authenticator.h"
+#include "chrome/browser/chromeos/login/default_pinned_apps_field_trial.h"
 #include "chrome/browser/chromeos/login/login_utils.h"
 #include "chrome/browser/chromeos/login/login_wizard.h"
 #include "chrome/browser/chromeos/login/screen_locker.h"
@@ -487,7 +488,7 @@ void ChromeBrowserMainPartsChromeos::PreMainMessageLoopRun() {
     CrasAudioHandler::Initialize(
         AudioDevicesPrefHandler::Create(g_browser_process->local_state()));
   } else {
-   AudioHandler::Initialize(
+    AudioHandler::Initialize(
        AudioPrefHandler::Create(g_browser_process->local_state()));
   }
 
@@ -851,6 +852,7 @@ void ChromeBrowserMainPartsChromeos::PostDestroyThreads() {
 
 void ChromeBrowserMainPartsChromeos::SetupPlatformFieldTrials() {
   SetupZramFieldTrial();
+  default_pinned_apps_field_trial::SetupTrial();
 }
 
 void ChromeBrowserMainPartsChromeos::SetupZramFieldTrial() {
diff --git a/chrome/browser/chromeos/extensions/default_app_order.cc b/chrome/browser/chromeos/extensions/default_app_order.cc
index 0d19745..a63df33 100644
--- a/chrome/browser/chromeos/extensions/default_app_order.cc
+++ b/chrome/browser/chromeos/extensions/default_app_order.cc
@@ -54,21 +54,21 @@ void GetDefault(std::vector<std::string>* app_ids) {
   const char* kDefaultAppOrder[] = {
     extension_misc::kChromeAppId,
     extension_misc::kWebStoreAppId,
-    "coobgpohoikkiipiblmjeljniedjpjpf",  // Search
-    "blpcfgokakmgnkcojhhkbfbldkacnbeo",  // Youtube
-    "pjkljhegncpnkpknbcohdijeoejaedia",  // Gmail
+    extension_misc::kGoogleSearchAppId,
+    extension_misc::kYoutubeAppId,
+    extension_misc::kGmailAppId,
     "ejjicmeblgpmajnghnpcppodonldlgfn",  // Calendar
     "kjebfhglflhjjjiceimfkgicifkhjlnm",  // Scratchpad
     "lneaknkopdijkpnocmklfnjbeapigfbh",  // Google Maps
     "apdfllckaahabafndbhieahigkjlhalf",  // Drive
-    "aohghmighlieiainnegkcijnfilokake",  // Docs
-    "felcaaldnbdncclmgdcncolpebgiejap",  // Sheets
-    "aapocclcgogkmnckokdopfmhonfmgoek",  // Slides
+    extension_misc::kGoogleDocAppId,
+    extension_misc::kGoogleSheetsAppId,
+    extension_misc::kGoogleSlidesAppId,
     "dlppkpafhbajpcmmoheippocdidnckmm",  // Google+
     "kbpgddbgniojgndnhlkjbkpknjhppkbk",  // Google+ Hangouts
     "hhaomjibdihmijegdhdafkllkbggdgoj",  // Files
     "hkhhlkdconhgemhegnplaldnmnmkaemd",  // Tips & Tricks
-    "icppfcnhkcmnfdhfhphakoifcfokfdhg",  // Play Music
+    extension_misc::kGooglePlayMusicAppId,
     "mmimngoggfoobjdlefbcabngfnmieonb",  // Play Books
     "fppdphmgcddhjeddoeghpjefkdlccljb",  // Play Movies
     "fobcpibfeplaikcclojfdhfdmbbeofai",  // Games
diff --git a/chrome/browser/chromeos/login/default_pinned_apps_field_trial.cc b/chrome/browser/chromeos/login/default_pinned_apps_field_trial.cc
new file mode 100644
index 0000000..f963ac9
--- /dev/null
+++ b/chrome/browser/chromeos/login/default_pinned_apps_field_trial.cc
@@ -0,0 +1,175 @@
+// 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/chromeos/login/default_pinned_apps_field_trial.h"
+
+#include "base/basictypes.h"
+#include "base/command_line.h"
+#include "base/memory/ref_counted.h"
+#include "base/metrics/field_trial.h"
+#include "base/metrics/histogram.h"
+#include "base/prefs/pref_registry_simple.h"
+#include "base/prefs/pref_service.h"
+#include "base/values.h"
+#include "chrome/browser/browser_process.h"
+#include "chrome/browser/prefs/scoped_user_pref_update.h"
+#include "chrome/browser/ui/ash/chrome_launcher_prefs.h"
+#include "chrome/common/chrome_switches.h"
+#include "chrome/common/extensions/extension_constants.h"
+
+namespace chromeos {
+namespace default_pinned_apps_field_trial {
+
+namespace {
+
+// Name of the default pinned app experiment.
+const char kExperimentName[] = "DefaultPinnedApps";
+
+// Name of a local state pref to store the list of users that participate
+// the experiment.
+const char kExperimentUsers[] = "DefaultPinnedAppsExperimentUsers";
+
+// Alternate default pinned apps.
+const char* kAlternateDefaultPinnedApps[] = {
+  extension_misc::kGmailAppId,
+  extension_misc::kGoogleDocAppId,
+  extension_misc::kGoogleSheetsAppId,
+  extension_misc::kGoogleSlidesAppId,
+  extension_misc::kGooglePlayMusicAppId,
+};
+
+// Global state of trial setup.
+bool trial_configured = false;
+int alternate_group = base::FieldTrial::kNotFinalized;
+
+// Returns true if user participates the experiment.
+bool IsUserInExperiment(const std::string& username) {
+  const base::ListValue* users =
+      g_browser_process->local_state()->GetList(kExperimentUsers);
+  return users && users->Find(base::StringValue(username)) != users->end();
+}
+
+// Adds user to the experiment user list.
+void AddUserToExperiment(const std::string& username) {
+  ListPrefUpdate users(g_browser_process->local_state(), kExperimentUsers);
+  users->AppendString(username);
+}
+
+// Gets click target type for given app id. Returns false if the app id is
+// not interesting.
+bool GetClickTargetForApp(const std::string& app_id,
+                          ClickTarget* click_target) {
+  static const struct AppIdToClickTarget {
+    const char* app_id;
+    ClickTarget click_target;
+  } kApps[] = {
+      { extension_misc::kChromeAppId, CHROME },
+      { extension_misc::kGmailAppId, GMAIL },
+      { extension_misc::kGoogleSearchAppId, SEARCH },
+      { extension_misc::kYoutubeAppId, YOUTUBE },
+      { extension_misc::kGoogleDocAppId, DOC },
+      { extension_misc::kGoogleSheetsAppId, SHEETS },
+      { extension_misc::kGoogleSlidesAppId, SLIDES },
+      { extension_misc::kGooglePlayMusicAppId, PLAY_MUSIC },
+  };
+
+  // kApps should define an app id for all click types except APP_LAUNCHER.
+  COMPILE_ASSERT(ARRAYSIZE_UNSAFE(kApps) == CLICK_TARGET_COUNT - 1,
+                 app_to_click_target_incorrect_size);
+
+  for (size_t i = 0; i < ARRAYSIZE_UNSAFE(kApps); ++i) {
+    if (app_id == kApps[i].app_id) {
+      *click_target = kApps[i].click_target;
+      return true;
+    }
+  }
+
+  return false;
+}
+
+}  // namespace
+
+void RegisterPrefs(PrefRegistrySimple* registry) {
+  registry->RegisterListPref(kExperimentUsers);
+}
+
+void SetupTrial() {
+  // No trial if multiple profiles are enabled.
+  if (CommandLine::ForCurrentProcess()->HasSwitch(::switches::kMultiProfiles))
+    return;
+
+  // SetupForUser should only be called once for single profile mode.
+  DCHECK(!trial_configured);
+
+  const base::FieldTrial::Probability kDivisor = 100;
+  scoped_refptr<base::FieldTrial> trial =
+      base::FieldTrialList::FactoryGetFieldTrial(
+          kExperimentName, kDivisor, "Existing", 2013, 12, 31, NULL);
+  trial->UseOneTimeRandomization();
+
+  // Split 50/50 between "Control" and "Alternamte" group for new user.
+  // Existing users already have their default pinned apps and have the trial
+  // disabled to go to "Existing" group.
+  trial->AppendGroup("Control", 50);
+  alternate_group = trial->AppendGroup("Alternate", 50);
+}
+
+void SetupForUser(const std::string& username, bool is_new_user) {
+  base::FieldTrial* trial = base::FieldTrialList::Find(kExperimentName);
+  if (!trial)
+    return;
+
+  trial_configured = true;
+
+  if (is_new_user) {
+    AddUserToExperiment(username);
+    return;
+  }
+
+  if (!IsUserInExperiment(username))
+    trial->Disable();
+}
+
+base::ListValue* GetAlternateDefaultPinnedApps() {
+  // This function is called for login manager profile, which happens
+  // before any user signs in. Returns NULL in this case. The case is covered
+  // by NULL trial check below but checking a boolean flag is faster.
+  if (!trial_configured)
+    return NULL;
+
+  base::FieldTrial* trial = base::FieldTrialList::Find(kExperimentName);
+  if (!trial || trial->group() != alternate_group)
+    return NULL;
+
+  scoped_ptr<base::ListValue> apps(new base::ListValue);
+  for (size_t i = 0; i < arraysize(kAlternateDefaultPinnedApps); ++i)
+    apps->Append(ash::CreateAppDict(kAlternateDefaultPinnedApps[i]));
+
+  return apps.release();
+}
+
+void RecordShelfClick(ClickTarget click_target) {
+  // The experiment does not include certain user types, such as public account,
+  // retail mode user, local user and ephemeral user.
+  if (!trial_configured)
+    return;
+
+  UMA_HISTOGRAM_ENUMERATION("Cros.ClickOnShelf",
+                            click_target,
+                            CLICK_TARGET_COUNT);
+}
+
+void RecordShelfAppClick(const std::string& app_id) {
+  ClickTarget click_target = CLICK_TARGET_COUNT;
+  if (GetClickTargetForApp(app_id, &click_target))
+    RecordShelfClick(click_target);
+}
+
+void ResetStateForTest() {
+  trial_configured = false;
+  alternate_group = base::FieldTrial::kNotFinalized;
+}
+
+}  // namespace default_pinned_apps_field_trial
+}  // namespace chromeos
diff --git a/chrome/browser/chromeos/login/default_pinned_apps_field_trial.h b/chrome/browser/chromeos/login/default_pinned_apps_field_trial.h
new file mode 100644
index 0000000..995bb96
--- /dev/null
+++ b/chrome/browser/chromeos/login/default_pinned_apps_field_trial.h
@@ -0,0 +1,59 @@
+// 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.
+
+#ifndef CHROME_BROWSER_CHROMEOS_LOGIN_DEFAULT_PINNED_APPS_FIELD_TRIAL_H_
+#define CHROME_BROWSER_CHROMEOS_LOGIN_DEFAULT_PINNED_APPS_FIELD_TRIAL_H_
+
+#include <string>
+
+namespace base {
+class ListValue;
+}
+
+class PrefRegistrySimple;
+
+namespace chromeos {
+namespace default_pinned_apps_field_trial {
+
+// Enumeration to track clicks on the shelf.
+enum ClickTarget {
+  CHROME = 0,
+  APP_LAUNCHER = 1,
+  GMAIL = 2,
+  SEARCH = 3,
+  YOUTUBE = 4,
+  DOC = 5,
+  SHEETS = 6,
+  SLIDES = 7,
+  PLAY_MUSIC = 8,
+  CLICK_TARGET_COUNT = 9
+};
+
+// Registers a local state that keeps track of users in experiment.
+void RegisterPrefs(PrefRegistrySimple* registry);
+
+// Creates the trail and setup groups.
+void SetupTrial();
+
+// Sets up the trial for a user. |username| is the email of the user.
+// |is_new_user| is a boolean flag to indicate whether the user is new to
+// the device. It is true when the user signs in the device for the first time.
+void SetupForUser(const std::string& username, bool is_new_user);
+
+// Returns the alternate default pinned apps if the current user is in
+// "Alternate" group. Otherwise, returns NULL. The caller takes the ownership
+// of the returned list.
+base::ListValue* GetAlternateDefaultPinnedApps();
+
+// Record UMA for shelf clicks.
+void RecordShelfClick(ClickTarget click_target);
+void RecordShelfAppClick(const std::string& app_id);
+
+// Resets global states from test.
+void ResetStateForTest();
+
+}  // namespace default_pinned_apps_field_trial
+}  // namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_LOGIN_DEFAULT_PINNED_APPS_FIELD_TRIAL_H_
diff --git a/chrome/browser/chromeos/login/default_pinned_apps_field_trial_unittest.cc b/chrome/browser/chromeos/login/default_pinned_apps_field_trial_unittest.cc
new file mode 100644
index 0000000..1406ca7
--- /dev/null
+++ b/chrome/browser/chromeos/login/default_pinned_apps_field_trial_unittest.cc
@@ -0,0 +1,91 @@
+// 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/chromeos/login/default_pinned_apps_field_trial.h"
+
+#include "base/memory/scoped_ptr.h"
+#include "base/metrics/field_trial.h"
+#include "base/prefs/testing_pref_service.h"
+#include "chrome/common/metrics/entropy_provider.h"
+#include "chrome/test/base/testing_browser_process.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace chromeos {
+
+class DefaultPinnedAppsFieldTrialTest : public testing::Test {
+ public:
+  DefaultPinnedAppsFieldTrialTest() {}
+  virtual ~DefaultPinnedAppsFieldTrialTest() {}
+
+  // testing::Test overrides:
+  virtual void SetUp() OVERRIDE {
+    CreateFieldTrialList();
+    CreateLocalState();
+  }
+  virtual void TearDown() OVERRIDE {
+    Reset();
+  }
+
+  void CreateFieldTrialList() {
+    if (trial_list_)
+      trial_list_.reset();
+    trial_list_.reset(new base::FieldTrialList(
+        new metrics::SHA1EntropyProvider("client_id")));
+    default_pinned_apps_field_trial::SetupTrial();
+  }
+
+  void CreateLocalState() {
+    local_state_.reset(new TestingPrefServiceSimple);
+    default_pinned_apps_field_trial::RegisterPrefs(local_state_->registry());
+    TestingBrowserProcess::GetGlobal()->SetLocalState(local_state_.get());
+  }
+
+  void Reset() {
+    TestingBrowserProcess::GetGlobal()->SetLocalState(NULL);
+    local_state_.reset();
+    trial_list_.reset();
+    default_pinned_apps_field_trial::ResetStateForTest();
+  }
+
+ private:
+  scoped_ptr<base::FieldTrialList> trial_list_;
+  scoped_ptr<TestingPrefServiceSimple> local_state_;
+
+  DISALLOW_COPY_AND_ASSIGN(DefaultPinnedAppsFieldTrialTest);
+};
+
+// Tests existing user gets to "Existing" group.
+TEST_F(DefaultPinnedAppsFieldTrialTest, ExistingUser) {
+  default_pinned_apps_field_trial::SetupForUser("existing@gmail.com",
+                                                false /* is_new_user */);
+  base::FieldTrial* trial = base::FieldTrialList::Find("DefaultPinnedApps");
+  ASSERT_TRUE(trial != NULL);
+  EXPECT_EQ("Existing", trial->group_name());
+}
+
+// Tests new user gets to either "Control" or "Alternate group. And the user
+// should get to the same group all the time.
+TEST_F(DefaultPinnedAppsFieldTrialTest, NewUser) {
+  const char* kTestUser = "new@gmail.com";
+  default_pinned_apps_field_trial::SetupForUser(kTestUser,
+                                                true /* is_new_user */);
+  base::FieldTrial* trial = base::FieldTrialList::Find("DefaultPinnedApps");
+  ASSERT_TRUE(trial != NULL);
+  const std::string allocated_group = trial->group_name();
+  EXPECT_TRUE("Control" == allocated_group || "Alternate" == allocated_group);
+
+  // Pretend user signs out and signs back in.
+  default_pinned_apps_field_trial::ResetStateForTest();
+  CreateFieldTrialList();
+
+  // This time, the user is no longer a new user.
+  default_pinned_apps_field_trial::SetupForUser(kTestUser,
+                                                false /* is_new_user */);
+
+  // But he/she should still be included in the trial and in the same group.
+  trial = base::FieldTrialList::Find("DefaultPinnedApps");
+  EXPECT_EQ(allocated_group, trial->group_name());
+}
+
+}  // namespace chromeos
diff --git a/chrome/browser/chromeos/login/user_manager_impl.cc b/chrome/browser/chromeos/login/user_manager_impl.cc
index addc810..cfdc9a9 100644
--- a/chrome/browser/chromeos/login/user_manager_impl.cc
+++ b/chrome/browser/chromeos/login/user_manager_impl.cc
@@ -27,6 +27,7 @@
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/chromeos/cros/cert_library.h"
 #include "chrome/browser/chromeos/cros/cros_library.h"
+#include "chrome/browser/chromeos/login/default_pinned_apps_field_trial.h"
 #include "chrome/browser/chromeos/login/login_display.h"
 #include "chrome/browser/chromeos/login/remove_user_delegate.h"
 #include "chrome/browser/chromeos/login/user_image_manager_impl.h"
@@ -1017,6 +1018,8 @@ void UserManagerImpl::RegularUserLoggedIn(const std::string& email,
     WallpaperManager::Get()->EnsureLoggedInUserWallpaperLoaded();
   }
 
+  default_pinned_apps_field_trial::SetupForUser(email, is_current_user_new_);
+
   // Make sure that new data is persisted to Local State.
   g_browser_process->local_state()->CommitPendingWrite();
 }
diff --git a/chrome/browser/extensions/default_apps.cc b/chrome/browser/extensions/default_apps.cc
index 3ecf9a0..9633d12 100644
--- a/chrome/browser/extensions/default_apps.cc
+++ b/chrome/browser/extensions/default_apps.cc
@@ -4,6 +4,9 @@
 
 #include "chrome/browser/extensions/default_apps.h"
 
+#include <set>
+#include <string>
+
 #include "base/command_line.h"
 #include "chrome/browser/browser_process.h"
 #include "components/user_prefs/pref_registry_syncable.h"
@@ -20,14 +23,11 @@
 
 namespace {
 
-const char kGmailId[] = "pjkljhegncpnkpknbcohdijeoejaedia";
-const char kSearchId[] = "coobgpohoikkiipiblmjeljniedjpjpf";
-const char kYoutubeId[] = "blpcfgokakmgnkcojhhkbfbldkacnbeo";
-
 // Returns true if the app was a default app in Chrome 22
 bool IsOldDefaultApp(const std::string& extension_id) {
-  return extension_id == kGmailId || extension_id == kSearchId
-      || extension_id == kYoutubeId;
+  return extension_id == extension_misc::kGmailAppId ||
+         extension_id == extension_misc::kGoogleSearchAppId ||
+         extension_id == extension_misc::kYoutubeAppId;
 }
 
 bool IsLocaleSupported() {
@@ -45,7 +45,7 @@ bool IsLocaleSupported() {
   return true;
 }
 
-} // namespace
+}  // namespace
 
 namespace default_apps {
 
diff --git a/chrome/browser/prefs/browser_prefs.cc b/chrome/browser/prefs/browser_prefs.cc
index fac503e..77581f3 100644
--- a/chrome/browser/prefs/browser_prefs.cc
+++ b/chrome/browser/prefs/browser_prefs.cc
@@ -122,6 +122,7 @@
 #include "chrome/browser/chromeos/audio/audio_pref_handler_impl.h"
 #include "chrome/browser/chromeos/customization_document.h"
 #include "chrome/browser/chromeos/display/display_preferences.h"
+#include "chrome/browser/chromeos/login/default_pinned_apps_field_trial.h"
 #include "chrome/browser/chromeos/login/login_utils.h"
 #include "chrome/browser/chromeos/login/oauth2_login_manager.h"
 #include "chrome/browser/chromeos/login/startup_utils.h"
@@ -247,6 +248,7 @@ void RegisterLocalState(PrefRegistrySimple* registry) {
   chromeos::DataPromoNotification::RegisterPrefs(registry);
   chromeos::DeviceOAuth2TokenService::RegisterPrefs(registry);
   chromeos::device_settings_cache::RegisterPrefs(registry);
+  chromeos::default_pinned_apps_field_trial::RegisterPrefs(registry);
   chromeos::language_prefs::RegisterPrefs(registry);
   chromeos::KioskAppManager::RegisterPrefs(registry);
   chromeos::LoginUtils::RegisterPrefs(registry);
diff --git a/chrome/browser/ui/ash/chrome_launcher_prefs.cc b/chrome/browser/ui/ash/chrome_launcher_prefs.cc
index 05994ea..b0dfdba 100644
--- a/chrome/browser/ui/ash/chrome_launcher_prefs.cc
+++ b/chrome/browser/ui/ash/chrome_launcher_prefs.cc
@@ -7,20 +7,32 @@
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/values.h"
+#include "chrome/common/extensions/extension_constants.h"
 #include "chrome/common/pref_names.h"
 #include "components/user_prefs/pref_registry_syncable.h"
 
+#if defined(OS_CHROMEOS)
+#include "chrome/browser/chromeos/login/default_pinned_apps_field_trial.h"
+#endif
+
 namespace {
 
 // App ID of default pinned apps.
 const char* kDefaultPinnedApps[] = {
-  "pjkljhegncpnkpknbcohdijeoejaedia",  // Gmail
-  "coobgpohoikkiipiblmjeljniedjpjpf",  // Search
-  "apdfllckaahabafndbhieahigkjlhalf",  // Doc
-  "blpcfgokakmgnkcojhhkbfbldkacnbeo",  // YouTube
+  extension_misc::kGmailAppId,
+  extension_misc::kGoogleSearchAppId,
+  extension_misc::kGoogleDocAppId,
+  extension_misc::kYoutubeAppId,
 };
 
 base::ListValue* CreateDefaultPinnedAppsList() {
+#if defined(OS_CHROMEOS)
+  base::ListValue* alternate = chromeos::default_pinned_apps_field_trial::
+      GetAlternateDefaultPinnedApps();
+  if (alternate)
+    return alternate;
+#endif
+
   scoped_ptr<base::ListValue> apps(new base::ListValue);
   for (size_t i = 0; i < arraysize(kDefaultPinnedApps); ++i)
     apps->Append(ash::CreateAppDict(kDefaultPinnedApps[i]));
diff --git a/chrome/browser/ui/ash/chrome_shell_delegate.cc b/chrome/browser/ui/ash/chrome_shell_delegate.cc
index 8657a67..56c4486 100644
--- a/chrome/browser/ui/ash/chrome_shell_delegate.cc
+++ b/chrome/browser/ui/ash/chrome_shell_delegate.cc
@@ -50,6 +50,10 @@
 #include "ui/aura/window.h"
 #include "ui/base/l10n/l10n_util.h"
 
+#if defined(OS_CHROMEOS)
+#include "chrome/browser/chromeos/login/default_pinned_apps_field_trial.h"
+#endif
+
 // static
 ChromeShellDelegate* ChromeShellDelegate::instance_ = NULL;
 
@@ -270,6 +274,10 @@ void ChromeShellDelegate::RecordUserMetricsAction(
     case ash::UMA_LAUNCHER_CLICK_ON_APPLIST_BUTTON:
       content::RecordAction(
           content::UserMetricsAction("Launcher_ClickOnApplistButton"));
+#if defined(OS_CHROMEOS)
+      chromeos::default_pinned_apps_field_trial::RecordShelfClick(
+          chromeos::default_pinned_apps_field_trial::APP_LAUNCHER);
+#endif
       break;
     case ash::UMA_MINIMIZE_PER_KEY:
       content::RecordAction(content::UserMetricsAction("Minimize_UsingKey"));
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.cc b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.cc
index f449388..c44eab4 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.cc
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app.cc
@@ -72,14 +72,16 @@
 #include "ui/base/l10n/l10n_util.h"
 #include "ui/views/corewm/window_animations.h"
 
+#if defined(OS_CHROMEOS)
+#include "chrome/browser/chromeos/login/default_pinned_apps_field_trial.h"
+#endif
+
 using extensions::Extension;
+using extension_misc::kGmailAppId;
 using content::WebContents;
 
 namespace {
 
-// The App ID for of the gMail application.
-const char kGmailAppId[] = "pjkljhegncpnkpknbcohdijeoejaedia";
-
 std::string GetPrefKeyForRootWindow(aura::RootWindow* root_window) {
   gfx::Display display = gfx::Screen::GetScreenFor(
       root_window)->GetDisplayNearestWindow(root_window);
@@ -901,6 +903,10 @@ void ChromeLauncherControllerPerApp::ActivateWindowOrMinimizeIfActive(
 
 void ChromeLauncherControllerPerApp::OnBrowserShortcutClicked(
     int event_flags) {
+#if defined(OS_CHROMEOS)
+  chromeos::default_pinned_apps_field_trial::RecordShelfClick(
+      chromeos::default_pinned_apps_field_trial::CHROME);
+#endif
   if (event_flags & ui::EF_CONTROL_DOWN) {
     CreateNewWindow();
     return;
@@ -927,7 +933,14 @@ void ChromeLauncherControllerPerApp::ItemSelected(const ash::LauncherItem& item,
     return;
   }
   DCHECK(HasItemController(item.id));
-  id_to_item_controller_map_[item.id]->Clicked(event);
+  LauncherItemController* item_controller = id_to_item_controller_map_[item.id];
+#if defined(OS_CHROMEOS)
+  if (!item_controller->app_id().empty()) {
+    chromeos::default_pinned_apps_field_trial::RecordShelfAppClick(
+        item_controller->app_id());
+  }
+#endif
+  item_controller->Clicked(event);
 }
 
 int ChromeLauncherControllerPerApp::GetBrowserShortcutResourceId() {
@@ -1300,7 +1313,7 @@ ChromeLauncherControllerPerApp::CreateAppShortcutLauncherItemWithType(
 void ChromeLauncherControllerPerApp::UpdateBrowserItemStatus() {
   // Determine the new browser's active state and change if necessary.
   size_t browser_index = ash::launcher::GetBrowserItemIndex(*model_);
-  DCHECK(browser_index >= 0);
+  DCHECK_GE(browser_index, 0u);
   ash::LauncherItem browser_item = model_->items()[browser_index];
   ash::LauncherItemStatus browser_status = ash::STATUS_CLOSED;
 
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app_unittest.cc b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app_unittest.cc
index eab87b9..d97c0df 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app_unittest.cc
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_app_unittest.cc
@@ -43,7 +43,6 @@ using extensions::Manifest;
 
 namespace {
 const int kExpectedAppIndex = 1;
-const char* gmail_app_id = "pjkljhegncpnkpknbcohdijeoejaedia";
 const char* offline_gmail_url = "https://mail.google.com/mail/mu/u";
 const char* gmail_url = "https://mail.google.com/mail/u";
 }
@@ -187,14 +186,14 @@ class ChromeLauncherControllerPerAppTest : public BrowserWithTestWindowTest {
     extension3_ = Extension::Create(base::FilePath(), Manifest::UNPACKED,
                                     manifest_gmail,
                                     Extension::NO_FLAGS,
-                                    gmail_app_id,
+                                    extension_misc::kGmailAppId,
                                     &error);
 
     // Fake search extension.
     extension4_ = Extension::Create(base::FilePath(), Manifest::UNPACKED,
                                     manifest,
                                     Extension::NO_FLAGS,
-                                    "coobgpohoikkiipiblmjeljniedjpjpf",
+                                    extension_misc::kGoogleSearchAppId,
                                     &error);
 
     // Create a default launcher controller; some tests will call
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.cc b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.cc
index 734035a..8e2eaca 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.cc
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser.cc
@@ -55,6 +55,10 @@
 #include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 
+#if defined(OS_CHROMEOS)
+#include "chrome/browser/chromeos/login/default_pinned_apps_field_trial.h"
+#endif
+
 using content::WebContents;
 using extensions::Extension;
 
@@ -862,6 +866,10 @@ void ChromeLauncherControllerPerBrowser::ActivateWindowOrMinimizeIfActive(
 
 void ChromeLauncherControllerPerBrowser::OnBrowserShortcutClicked(
     int event_flags) {
+#if defined(OS_CHROMEOS)
+  chromeos::default_pinned_apps_field_trial::RecordShelfClick(
+      chromeos::default_pinned_apps_field_trial::CHROME);
+#endif
   if (event_flags & ui::EF_CONTROL_DOWN) {
     CreateNewWindow();
     return;
@@ -884,7 +892,14 @@ void ChromeLauncherControllerPerBrowser::ItemSelected(
     const ash::LauncherItem& item,
     const ui::Event& event) {
   DCHECK(HasItemController(item.id));
-  id_to_item_controller_map_[item.id]->Clicked(event);
+  LauncherItemController* item_controller = id_to_item_controller_map_[item.id];
+#if defined(OS_CHROMEOS)
+  if (!item_controller->app_id().empty()) {
+    chromeos::default_pinned_apps_field_trial::RecordShelfAppClick(
+        item_controller->app_id());
+  }
+#endif
+  item_controller->Clicked(event);
 }
 
 int ChromeLauncherControllerPerBrowser::GetBrowserShortcutResourceId() {
diff --git a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser_unittest.cc b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser_unittest.cc
index dea21489..b71fa11 100644
--- a/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser_unittest.cc
+++ b/chrome/browser/ui/ash/launcher/chrome_launcher_controller_per_browser_unittest.cc
@@ -72,13 +72,13 @@ class ChromeLauncherControllerPerBrowserTest : public testing::Test {
     extension3_ = Extension::Create(base::FilePath(), Manifest::UNPACKED,
                                     manifest,
                                     Extension::NO_FLAGS,
-                                    "pjkljhegncpnkpknbcohdijeoejaedia",
+                                    extension_misc::kGmailAppId,
                                     &error);
     // Fake search extension.
     extension4_ = Extension::Create(base::FilePath(), Manifest::UNPACKED,
                                     manifest,
                                     Extension::NO_FLAGS,
-                                    "coobgpohoikkiipiblmjeljniedjpjpf",
+                                    extension_misc::kGoogleSearchAppId,
                                     &error);
   }
 
diff --git a/chrome/chrome_browser_chromeos.gypi b/chrome/chrome_browser_chromeos.gypi
index 0180d89..50e8a30 100644
--- a/chrome/chrome_browser_chromeos.gypi
+++ b/chrome/chrome_browser_chromeos.gypi
@@ -388,6 +388,8 @@
         'browser/chromeos/login/captive_portal_window_proxy.h',
         'browser/chromeos/login/chrome_restart_request.cc',
         'browser/chromeos/login/chrome_restart_request.h',
+        'browser/chromeos/login/default_pinned_apps_field_trial.cc',
+        'browser/chromeos/login/default_pinned_apps_field_trial.h',
         'browser/chromeos/login/default_user_images.cc',
         'browser/chromeos/login/default_user_images.h',
         'browser/chromeos/login/enrollment/enrollment_screen.cc',
diff --git a/chrome/chrome_tests_unit.gypi b/chrome/chrome_tests_unit.gypi
index 25f7754..ce7d17a 100644
--- a/chrome/chrome_tests_unit.gypi
+++ b/chrome/chrome_tests_unit.gypi
@@ -626,6 +626,7 @@
         'browser/chromeos/kiosk_mode/kiosk_mode_idle_logout_unittest.cc',
         'browser/chromeos/kiosk_mode/kiosk_mode_settings_unittest.cc',
         'browser/chromeos/language_preferences_unittest.cc',
+        'browser/chromeos/login/default_pinned_apps_field_trial_unittest.cc',
         'browser/chromeos/login/existing_user_controller_auto_login_unittest.cc',
         'browser/chromeos/login/hwid_checker_unittest.cc',
         'browser/chromeos/login/merge_session_load_page_unittest.cc',
diff --git a/chrome/common/extensions/extension_constants.cc b/chrome/common/extensions/extension_constants.cc
index c6e8847..844197b 100644
--- a/chrome/common/extensions/extension_constants.cc
+++ b/chrome/common/extensions/extension_constants.cc
@@ -105,7 +105,7 @@ const char kGeneratedBackgroundPageFilename[] =
 
 const char kModulesDir[] = "_modules";
 
-}
+}  // namespace extension_filenames
 
 // These must match the values expected by the chrome.management extension API.
 namespace extension_info_keys {
@@ -124,11 +124,20 @@ namespace extension_info_keys {
 }  // namespace extension_filenames
 
 namespace extension_misc {
+
 const char kBookmarkManagerId[] = "eemcgdkfndhakfknompkggombfjjjeno";
+const char kChromeAppId[] = "mgndgikekgjfcpckkfioiadnlibdjbkf";
 const char kCitrixReceiverAppId[] = "haiffjcadagjlijoggckpgfnoeiflnem";
 const char kCitrixReceiverAppBetaId[] = "gnedhmakppccajfpfiihfcdlnpgomkcf";
 const char kCitrixReceiverAppDevId[] = "fjcibdnjlbfnbfdjneajpipnlcppleek";
+const char kCloudPrintAppId[] = "mfehgcgbbipciphmccgaenjidiccnmng";
 const char kEnterpriseWebStoreAppId[] = "afchcafgojfnemjkcbhfekplkmjaldaa";
+const char kGmailAppId[] = "pjkljhegncpnkpknbcohdijeoejaedia";
+const char kGoogleDocAppId[] = "aohghmighlieiainnegkcijnfilokake";
+const char kGooglePlayMusicAppId[] = "icppfcnhkcmnfdhfhphakoifcfokfdhg";
+const char kGoogleSearchAppId[] = "coobgpohoikkiipiblmjeljniedjpjpf";
+const char kGoogleSheetsAppId[] = "felcaaldnbdncclmgdcncolpebgiejap";
+const char kGoogleSlidesAppId[] = "aapocclcgogkmnckokdopfmhonfmgoek";
 const char kHTermAppId[] = "pnhechapfaindjhompbnflcldabbghjo";
 const char kHTermDevAppId[] = "okddffdblfhhnmhodogpojmfkjmhinfp";
 const char kCroshBuiltinAppId[] = "nkoccljplnhpfnfiajclkommnmllphnl";
@@ -136,12 +145,12 @@ const char kQuickOfficeComponentExtensionId[] =
     "bpmcpldpdmajfigpchkicefoigmkfalc";
 const char kQuickOfficeDevExtensionId[] = "ionpfmkccalenbmnddpbmocokhaknphg";
 const char kQuickOfficeExtensionId[] = "gbkeegbaiigmenfmjfclcdgdpimamgkj";
+const char kSettingsAppId[] = "ennkphjdgehloodpbhlhldgbnhmacadg";
 const char kStreamsPrivateTestExtensionId[] =
     "oickdpebdnfbgkcaoklfcdhjniefkcji";
 const char kWebStoreAppId[] = "ahfgeienlihckogmohjhadlkjgocpleb";
-const char kCloudPrintAppId[] = "mfehgcgbbipciphmccgaenjidiccnmng";
-const char kChromeAppId[] = "mgndgikekgjfcpckkfioiadnlibdjbkf";
-const char kSettingsAppId[] = "ennkphjdgehloodpbhlhldgbnhmacadg";
+const char kYoutubeAppId[] = "blpcfgokakmgnkcojhhkbfbldkacnbeo";
+
 const char kAppLaunchHistogram[] = "Extensions.AppLaunch";
 const char kPlatformAppLaunchHistogram[] = "Apps.AppLaunch";
 #if defined(OS_CHROMEOS)
diff --git a/chrome/common/extensions/extension_constants.h b/chrome/common/extensions/extension_constants.h
index 8ce965f..9566f17 100644
--- a/chrome/common/extensions/extension_constants.h
+++ b/chrome/common/extensions/extension_constants.h
@@ -94,6 +94,9 @@ namespace extension_misc {
   // The extension id of the bookmark manager.
   extern const char kBookmarkManagerId[];
 
+  // The extension id of the Chrome component application.
+  extern const char kChromeAppId[];
+
   // The extension id of the Citrix Receiver application.
   extern const char kCitrixReceiverAppId[];
 
@@ -103,9 +106,30 @@ namespace extension_misc {
   // The extension id of the dev Citrix Receiver application.
   extern const char kCitrixReceiverAppDevId[];
 
+  // The extension id of the Cloud Print component application.
+  extern const char kCloudPrintAppId[];
+
   // The extension id of the Enterprise Web Store component application.
   extern const char kEnterpriseWebStoreAppId[];
 
+  // The extension id of GMail application.
+  extern const char kGmailAppId[];
+
+  // The extension id of the Google Doc application.
+  extern const char kGoogleDocAppId[];
+
+  // The extension id of the Google Play Music application.
+  extern const char kGooglePlayMusicAppId[];
+
+  // The extension id of the Google Search application.
+  extern const char kGoogleSearchAppId[];
+
+  // The extension id of the Google Sheets application.
+  extern const char kGoogleSheetsAppId[];
+
+  // The extension id of the Google Slides application.
+  extern const char kGoogleSlidesAppId[];
+
   // The extension id of the HTerm app for ChromeOS.
   extern const char kHTermAppId[];
 
@@ -124,20 +148,17 @@ namespace extension_misc {
   // The extension id of the Office Viewer extension.
   extern const char kQuickOfficeExtensionId[];
 
+  // The extension id of the settings application.
+  extern const char kSettingsAppId[];
+
   // The extension id used for testing streamsPrivate
   extern const char kStreamsPrivateTestExtensionId[];
 
   // The extension id of the Web Store component application.
   extern const char kWebStoreAppId[];
 
-  // The extension id of the Cloud Print component application.
-  extern const char kCloudPrintAppId[];
-
-  // The extension id of the Chrome component application.
-  extern const char kChromeAppId[];
-
-  // The extension id of the settings application.
-  extern const char kSettingsAppId[];
+  // The extension id of the Youtube application.
+  extern const char kYoutubeAppId[];
 
   // Note: this structure is an ASN.1 which encodes the algorithm used
   // with its parameters. This is defined in PKCS #1 v2.1 (RFC 3447).
@@ -305,7 +326,6 @@ namespace extension_misc {
   // List of sizes for extension icons that can be defined in the manifest.
   extern const int kScriptBadgeIconSizes[];
   extern const size_t kNumScriptBadgeIconSizes;
-
-}  // extension_misc
+}  // namespace extension_misc
 
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_CONSTANTS_H_
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index 524912e..5952c4c 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -459,6 +459,10 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Cros.ClickOnShelf" enum="CrosShelfClickTarget">
+  <summary>Chrome OS shelf clicks.</summary>
+</histogram>
+
 <histogram name="CrosDisks.ArchiveType" enum="CrosDisksArchiveType">
   <summary>
     The type of archive file that Chrome OS cros-disks daemon is requested to
@@ -7680,6 +7684,18 @@ other types of suffix sets.
   <int value="0" label="ModemManagerCommandSendFailure"/>
 </enum>
 
+<enum name="CrosShelfClickTarget" type="int">
+  <int value="0" label="Chrome"/>
+  <int value="1" label="AppLauncher"/>
+  <int value="2" label="Gmail"/>
+  <int value="3" label="Search"/>
+  <int value="4" label="Youtube"/>
+  <int value="5" label="Doc"/>
+  <int value="6" label="Sheets"/>
+  <int value="7" label="Slides"/>
+  <int value="8" label="PlayMusic"/>
+</enum>
+
 <enum name="DomainBoundCerts.GetCertResult" type="int">
   <int value="0" label="SYNC_SUCCESS"/>
   <int value="1" label="ASYNC_SUCCESS"/>
@@ -10933,6 +10949,13 @@ other types of suffix sets.
   <affected-histogram name="PLT.LoadType"/>
 </fieldtrial>
 
+<fieldtrial name="DefaultPinnedApps">
+  <group name="Existing"/>
+  <group name="Control"/>
+  <group name="Alternate"/>
+  <affected-histogram name="Cros.ClickOnShelf"/>
+</fieldtrial>
+
 <fieldtrial name="DnsImpact2">
   <group name="disabled_prefetch"
       label="DNS pre-resolving is disabled in these clients"/>