Implement the UI logic behind the Sign In promo in the password bubble

components/password_manager/core/browser/password_bubble_experiment.h

Index: components/password_manager/core/browser/password_bubble_experiment.h
diff --git a/components/password_manager/core/browser/password_bubble_experiment.h b/components/password_manager/core/browser/password_bubble_experiment.h
index 24877bb733ed3d1ddee3332cb8128864f5d1b46a..7e68da419f1559a3a9c7f7be1ff6f7ebe2cfef7a 100644
--- a/components/password_manager/core/browser/password_bubble_experiment.h
+++ b/components/password_manager/core/browser/password_bubble_experiment.h
@@ -15,6 +15,8 @@ class SyncService;
 namespace password_bubble_experiment {
 
 extern const char kBrandingExperimentName[];
+extern const char kChromeSignInPasswordPromoExperimentName[];
+extern const char kChromeSignInPasswordPromoThresholdParam[];
 extern const char kSmartBubbleExperimentName[];
 extern const char kSmartBubbleThresholdParam[];
 extern const char kSmartLockBrandingGroupName[];
@@ -71,6 +73,9 @@ void RecordAutoSignInPromptFirstRunExperienceWasShown(PrefService* prefs);
 // Turns off the auto signin experience setting.
 void TurnOffAutoSignin(PrefService* prefs);
 
+// Returns true if the Chrome Sign In promo should be shown.
+bool ShouldShowChromeSignInPasswordPromo(PrefService* prefs);
+
 }  // namespace password_bubble_experiment
 
 #endif  // COMPONENTS_PASSWORD_MANAGER_CORE_BROWSER_PASSWORD_BUBBLE_EXPERIMENT_H_