Fix ios_chrome_unittests to crash on DCHECK failure.

ios/chrome/browser/ui/ntp/notification_promo_whats_new_unittest.mm

 // Copyright (c) 2016 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.
 
 #import "ios/chrome/browser/ui/ntp/notification_promo_whats_new.h"
 
 #include <map>
 
+#include "base/bind.h"
 #include "base/metrics/field_trial.h"
-#include "base/test/user_action_tester.h"
+#include "base/metrics/user_metrics.h"
 #include "base/time/time.h"
 #include "base/values.h"
 #include "components/metrics/metrics_pref_names.h"
 #include "components/prefs/pref_registry_simple.h"
 #include "components/prefs/testing_pref_service.h"
 #include "components/variations/variations_associated_data.h"
 #include "ios/chrome/browser/ui/commands/ios_command_ids.h"
 #include "ios/chrome/grit/ios_chromium_strings.h"
 #include "ios/public/provider/chrome/browser/images/whats_new_icon.h"
 #include "testing/platform_test.h"
 #include "ui/base/l10n/l10n_util.h"
 #include "url/gurl.h"
 
 namespace {
 
 // Test fixture for NotificationPromoWhatsNew.
 class NotificationPromoWhatsNewTest : public PlatformTest {
  public:
   NotificationPromoWhatsNewTest()
       : promo_(&local_state_),
+        action_callback_(
+            base::Bind(&NotificationPromoWhatsNewTest::OnUserAction,
+                       base::Unretained(this))),
         field_trial_list_(new base::FieldTrialList(NULL)) {
     ios::NotificationPromo::RegisterPrefs(local_state_.registry());
     local_state_.registry()->RegisterInt64Pref(metrics::prefs::kInstallDate, 0);
+    base::AddActionCallback(action_callback_);
   }
 
   ~NotificationPromoWhatsNewTest() override {
+    base::RemoveActionCallback(action_callback_);
     variations::testing::ClearAllVariationParams();
   }
 
   void TearDown() override {
     promo_.ClearAndInitFromJson(base::DictionaryValue());
     PlatformTest::TearDown();
   }
 
   // Sets up a mock finch trial and inits the NotificationPromoWhatsNew. All
   // parameters will be added to the list of finch parameters.
@@ skipping 44 matching lines @@
       EXPECT_EQ(url, promo_.url().spec());
     else
       EXPECT_EQ(command_id, promo_.command_id());
 
     EXPECT_EQ(valid, promo_.CanShow());
     // |icon()| is set only if the promo is valid.
     if (valid)
       EXPECT_EQ(icon, promo_.icon());
   }
 
+  void OnUserAction(const std::string& user_action) {
+    user_action_count_map_[user_action]++;
+  }
+
+  int GetUserActionCount(const std::string& user_action) {
+    return user_action_count_map_[user_action];
+  }
+
  protected:
   TestingPrefServiceSimple local_state_;
   NotificationPromoWhatsNew promo_;
+  base::ActionCallback action_callback_;
+  std::map<std::string, int> user_action_count_map_;
 
  private:
   std::unique_ptr<base::FieldTrialList> field_trial_list_;
 };
 
 // Test that a command-based, valid promo is shown with the correct text.
 TEST_F(NotificationPromoWhatsNewTest, NotificationPromoCommandTest) {
   Init("3 Aug 1999 9:26:06 GMT", "3 Aug 2199 9:26:06 GMT",
        "IDS_IOS_APP_RATING_PROMO_STRING", "0", "chrome_command", "",
        "ratethisapp", "RateThisAppPromo", "logo", "0", "0");
@@ skipping 82 matching lines @@
   // the promo can show starting at 2 days after install date.
   EXPECT_FALSE(promo_.CanShow());
 }
 
 // Test that user actions are recorded when promo is viewed and closed.
 TEST_F(NotificationPromoWhatsNewTest, NotificationPromoMetricTest) {
   Init("3 Aug 1999 9:26:06 GMT", "3 Aug 2199 9:26:06 GMT",
        "IDS_IOS_APP_RATING_PROMO_STRING", "0", "chrome_command", "",
        "ratethisapp", "RateThisAppPromo", "logo", "0", "0");
 
-  base::UserActionTester user_action_tester;
   // Assert that promo is appropriately set up to be viewed.
   ASSERT_TRUE(promo_.CanShow());
   promo_.HandleViewed();
-  EXPECT_EQ(1, user_action_tester.GetActionCount(
-                   "WhatsNewPromoViewed_RateThisAppPromo"));
+  EXPECT_EQ(1, GetUserActionCount("WhatsNewPromoViewed_RateThisAppPromo"));
 
   // Verify that the promo closed user action count is 0 before |HandleClosed()|
   // is called.
-  EXPECT_EQ(0, user_action_tester.GetActionCount(
-                   "WhatsNewPromoClosed_RateThisAppPromo"));
+  EXPECT_EQ(0, GetUserActionCount("WhatsNewPromoClosed_RateThisAppPromo"));
   promo_.HandleClosed();
-  EXPECT_EQ(1, user_action_tester.GetActionCount(
-                   "WhatsNewPromoClosed_RateThisAppPromo"));
+  EXPECT_EQ(1, GetUserActionCount("WhatsNewPromoClosed_RateThisAppPromo"));
 }
 
 }  // namespace