[Android] Get rid of explicit register/unregister in SignInPreference

Replace register and unregister with onAttached and onDetached methods
in SignInPreference

Bug: 1127990
Change-Id: If4f385691b44ea2845428c9c76143d566c82cce5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2409964
Commit-Queue: Tanmoy Mollik <triploblastic@chromium.org>
Reviewed-by: Marc Treib <treib@chromium.org>
Cr-Commit-Position: refs/heads/master@{#822664}

chrome/android/java/src/org/chromium/chrome/browser/settings/MainSettings.java

@@ -131,7 +131,6 @@ public class MainSettings extends PreferenceFragmentCompat
                 Profile.getLastUsedRegularProfile());
         if (signinManager.isSigninSupported()) {
             signinManager.addSignInStateObserver(this);
-            mSignInPreference.registerForUpdates();
         }
         ProfileSyncService syncService = ProfileSyncService.get();
         if (syncService != null) {
@@ -146,7 +145,6 @@ public class MainSettings extends PreferenceFragmentCompat
                 Profile.getLastUsedRegularProfile());
         if (signinManager.isSigninSupported()) {
             signinManager.removeSignInStateObserver(this);
-            mSignInPreference.unregisterForUpdates();
         }
         ProfileSyncService syncService = ProfileSyncService.get();
         if (syncService != null) {
@@ -409,14 +407,10 @@ public class MainSettings extends PreferenceFragmentCompat
         // "You and Google" section header if the personalized sync promo is shown.
         boolean isShowingPersonalizedPromo =
                 mSignInPreference.getState() == SignInPreference.State.PERSONALIZED_PROMO;
-        if (ChromeFeatureList.isEnabled(ChromeFeatureList.MOBILE_IDENTITY_CONSISTENCY)) {
-            findPreference(PREF_ACCOUNT_AND_GOOGLE_SERVICES_SECTION)
-                    .setVisible(!isShowingPersonalizedPromo);
-        } else if (isShowingPersonalizedPromo) {
-            removePreferenceIfPresent(PREF_ACCOUNT_SECTION);
-        } else {
-            addPreferenceIfAbsent(PREF_ACCOUNT_SECTION);
-        }
+        String prefName = ChromeFeatureList.isEnabled(ChromeFeatureList.MOBILE_IDENTITY_CONSISTENCY)
+                ? PREF_ACCOUNT_AND_GOOGLE_SERVICES_SECTION
+                : PREF_ACCOUNT_SECTION;
+        findPreference(prefName).setVisible(!isShowingPersonalizedPromo);
     }
 
     // TemplateUrlService.LoadListener implementation.

chrome/android/java/src/org/chromium/chrome/browser/sync/settings/SignInPreference.java

@@ -94,10 +94,10 @@ public class SignInPreference
         mState = State.SIGNED_IN;
     }
 
-    /**
-     * Starts listening for updates to the sign-in and sync state.
-     */
-    public void registerForUpdates() {
+    @Override
+    public void onAttached() {
+        super.onAttached();
+
         mAccountManagerFacade.addObserver(this);
         IdentityServicesProvider.get()
                 .getSigninManager(Profile.getLastUsedRegularProfile())
@@ -114,11 +114,10 @@ public class SignInPreference
         update();
     }
 
-    /**
-     * Stops listening for updates to the sign-in and sync state. Every call to registerForUpdates()
-     * must be matched with a call to this method.
-     */
-    public void unregisterForUpdates() {
+    @Override
+    public void onDetached() {
+        super.onDetached();
+
         mAccountManagerFacade.removeObserver(this);
         IdentityServicesProvider.get()
                 .getSigninManager(Profile.getLastUsedRegularProfile())

chrome/android/java/src/org/chromium/chrome/browser/sync/settings/SyncAndServicesSettings.java

@@ -337,7 +337,6 @@ public class SyncAndServicesSettings extends PreferenceFragmentCompat
     public void onStart() {
         super.onStart();
         mProfileSyncService.addSyncStateChangedListener(this);
-        mSigninPreference.registerForUpdates();
 
         if (!mIsFromSigninScreen
                 || IdentityServicesProvider.get()
@@ -363,7 +362,6 @@ public class SyncAndServicesSettings extends PreferenceFragmentCompat
     public void onStop() {
         super.onStop();
 
-        mSigninPreference.unregisterForUpdates();
         mProfileSyncService.removeSyncStateChangedListener(this);
     }
 

chrome/android/javatests/src/org/chromium/chrome/browser/settings/MainSettingsFragmentTest.java

@@ -220,8 +220,8 @@ public class MainSettingsFragmentTest {
 
         // SignInPreference status check.
         // As the user is not signed in, sign in promo will show, section header will be hidden.
-        Assert.assertNull("Account section header should be hidden.",
-                mMainSettings.findPreference(MainSettings.PREF_ACCOUNT_SECTION));
+        Assert.assertFalse("Account section header should be hidden.",
+                mMainSettings.findPreference(MainSettings.PREF_ACCOUNT_SECTION).isVisible());
 
         // Assert for "Basics" section
         assertSettingsExists(MainSettings.PREF_SEARCH_ENGINE, SearchEngineSettings.class);
@@ -379,8 +379,8 @@ public class MainSettingsFragmentTest {
                 (SignInPreference) assertSettingsExists(MainSettings.PREF_SIGN_IN, null);
         Assert.assertEquals("SignInPreference should be at the personalized promo state. ",
                 signInPreference.getState(), State.PERSONALIZED_PROMO);
-        Assert.assertNull("Account section header should be hidden when promo is shown.",
-                mMainSettings.findPreference(MainSettings.PREF_ACCOUNT_SECTION));
+        Assert.assertFalse("Account section header should be hidden when promo is shown.",
+                mMainSettings.findPreference(MainSettings.PREF_ACCOUNT_SECTION).isVisible());
 
         // SignIn to see the changes
         mSyncTestRule.setUpAccountAndEnableSyncForTesting();