[Sync] Ensure the user has a chance to change their settings on Android.

chrome/android/java/src/org/chromium/chrome/browser/signin/AccountManagementFragment.java

 // Copyright 2015 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.
 
 package org.chromium.chrome.browser.signin;
 
 import android.accounts.Account;
 import android.annotation.TargetApi;
 import android.app.Activity;
 import android.app.Dialog;
@@ skipping 101 matching lines @@
     public static final String PREF_SYNC_SETTINGS = "sync_settings";
 
     private int mGaiaServiceType;
 
     private ArrayList<Preference> mAccountsListPreferences = new ArrayList<Preference>();
 
     @Override
     public void onCreate(Bundle savedState) {
         super.onCreate(savedState);
 
+        // Prevent sync from starting if it hasn't already to give the user a chance to change
+        // their sync settings.
+        ProfileSyncService syncService = ProfileSyncService.get();
+        if (syncService != null) {
+            syncService.setSetupInProgress(true);
+        }
+
         mGaiaServiceType = AccountManagementScreenHelper.GAIA_SERVICE_TYPE_NONE;
         if (getArguments() != null) {
             mGaiaServiceType =
                     getArguments().getInt(SHOW_GAIA_SERVICE_TYPE_EXTRA, mGaiaServiceType);
         }
 
         AccountManagementScreenHelper.logEvent(
                 ProfileAccountManagementMetrics.VIEW,
                 mGaiaServiceType);
 
@@ skipping 17 matching lines @@
     public void onPause() {
         super.onPause();
         SigninManager.get(getActivity()).removeSignInStateObserver(this);
         ProfileDownloader.removeObserver(this);
         ProfileSyncService syncService = ProfileSyncService.get();
         if (syncService != null) {
             syncService.removeSyncStateChangedListener(this);
         }
     }
 
+    @Override
+    public void onDestroy() {
+        super.onDestroy();
+
+        // Allow sync to begin syncing if it hasn't yet.
+        ProfileSyncService syncService = ProfileSyncService.get();
+        if (syncService != null) {
+            syncService.setSetupInProgress(false);
+        }
+    }
+
     /**
      * Initiate fetching the user accounts data (images and the full name).
      * Fetched data will be sent to observers of ProfileDownloader.
      *
      * @param profile Profile to use.
      */
     private static void startFetchingAccountsInformation(Context context, Profile profile) {
         Account[] accounts = AccountManagerHelper.get(context).getGoogleAccounts();
         for (int i = 0; i < accounts.length; i++) {
             startFetchingAccountInformation(context, profile, accounts[i].name);
@@ skipping 313 matching lines @@
                     ProfileAccountManagementMetrics.SIGNOUT_CANCEL,
                     mGaiaServiceType);
         }
     }
 
     // ProfileSyncServiceListener implementation:
 
     @Override
     public void syncStateChanged() {
         SyncPreference pref = (SyncPreference) findPreference(PREF_SYNC_SETTINGS);
-        pref.updateSyncSummaryAndIcon();
+        if (pref != null) {

[gogerald1, 2016/05/20 13:10:19]

Curious, under what circumstance this could be null?

[maxbogue, 2016/05/20 15:53:00]

It's always null before the addPreferencesFromResource() call in update() in
onResume(). Since setting setupInProgress to true triggers syncStateChanged(), I
was hitting a NullPointerException 100% of the time in manual testing.

+            pref.updateSyncSummaryAndIcon();
+        }
 
         // TODO(crbug/557784): Show notification for sync error
     }
 
     // SignInStateObserver implementation:
 
     @Override
     public void onSignedIn() {
         update();
     }
@@ skipping 194 matching lines @@
      * @param context A context
      * @param isAllowed True if the sign out is not disabled due to a child/EDU account
      */
     public static void setSignOutAllowedPreferenceValue(Context context, boolean isAllowed) {
         ContextUtils.getAppSharedPreferences()
                 .edit()
                 .putBoolean(SIGN_OUT_ALLOWED, isAllowed)
                 .apply();
     }
 }