[Android backup] Restore nothing if signed in user isn't valid

chrome/android/java/src/org/chromium/chrome/browser/ChromeBackupAgent.java

 // Copyright 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.
 
 package org.chromium.chrome.browser;
 
+import android.accounts.Account;
+import android.accounts.AccountManager;
 import android.annotation.TargetApi;
 import android.app.backup.BackupAgent;
 import android.app.backup.BackupDataInput;
 import android.app.backup.BackupDataOutput;
 import android.content.SharedPreferences;
 import android.os.Build;
 import android.os.ParcelFileDescriptor;
 
 import org.chromium.base.ContextUtils;
 import org.chromium.base.Log;
+import org.chromium.base.VisibleForTesting;
 import org.chromium.chrome.browser.firstrun.FirstRunSignInProcessor;
 import org.chromium.chrome.browser.firstrun.FirstRunStatus;
 import org.chromium.chrome.browser.preferences.privacy.PrivacyPreferences;
 import org.chromium.sync.signin.ChromeSigninController;
 
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.HashSet;
 import java.util.Set;
 
 /**
  * Backup agent for Chrome, filters the restored backup to remove preferences that should not have
  * been restored.
+ *
+ * Note: Nothing in this class can depend on the ChromeApplication instance having been created.
+ * During restore Android creates a special instance of the Chrome application with its own
+ * Android defined application class, which is not derived from ChromeApplication.
  */
 @TargetApi(Build.VERSION_CODES.LOLLIPOP)
 public class ChromeBackupAgent extends BackupAgent {
 
     private static final String TAG = "ChromeBackupAgent";
 
     // Lists of preferences that should be restored unchanged.
 
     // TODO(aberent): At present this only restores the signed in user, and the FRE settings
     // (whether is has been completed, and whether the user disabled crash dump reporting). It
-    // should restore all non-device specific aspects of the user's state. This will involve both
-    // restoring many more Android preferences and many Chrome preferences (in Chrome's JSON
-    // preference file).
+    // should also restore all the user's sync choices. This will involve restoring a number of
+    // Chrome preferences (in Chrome's JSON preference file) in addition to the Android preferences
+    // currently restored.
     private static final String[] RESTORED_ANDROID_PREFS = {
             PrivacyPreferences.PREF_CRASH_DUMP_UPLOAD,
             FirstRunStatus.FIRST_RUN_FLOW_COMPLETE,
             FirstRunSignInProcessor.FIRST_RUN_FLOW_SIGNIN_SETUP,
     };
 
+    private static boolean sAllowChromeApplication = false;
+
     @Override
     public void onBackup(ParcelFileDescriptor oldState, BackupDataOutput data,
             ParcelFileDescriptor newState) throws IOException {
         // No implementation needed for Android 6.0 Auto Backup. Used only on older versions of
         // Android Backup
     }
 
     @Override
     public void onRestore(BackupDataInput data, int appVersionCode, ParcelFileDescriptor newState)
             throws IOException {
         // No implementation needed for Android 6.0 Auto Backup. Used only on older versions of
         // Android Backup
     }
 
+    // May be overriden by downstream products that access account information in a different way.
+    protected Account[] getAccounts() {
+        Log.d(TAG, "Getting accounts from AccountManager");
+        AccountManager manager = (AccountManager) getSystemService(ACCOUNT_SERVICE);
+        return manager.getAccounts();
+    }
+
+    private boolean accountExistsOnDevice(String userName) {
+        // This cannot use AccountManagerHelper, since that depends on ChromeApplication.
+        for (Account account: getAccounts()) {
+            if (account.name.equals(userName)) return true;
+        }
+        return false;
+    }
+
     @Override
     public void onRestoreFinished() {
+        if (getApplicationContext() instanceof ChromeApplication && !sAllowChromeApplication) {
+            // This should never happen in real use, but will happen during testing if Chrome is
+            // already running (even in background, started to provide a service, for example).
+            Log.w(TAG, "Running with wrong type of Application class");
+            return;
+        }
+        // This is running without a ChromeApplication instance, so this has to be done here.
+        ContextUtils.initApplicationContext(getApplicationContext());
         SharedPreferences sharedPrefs = ContextUtils.getAppSharedPreferences();
         Set<String> prefNames = sharedPrefs.getAll().keySet();
         // Save the user name for later restoration.
         String userName = sharedPrefs.getString(ChromeSigninController.SIGNED_IN_ACCOUNT_KEY, null);
+        Log.d(TAG, "Previous signed in user name = " + userName);
+        // If the user hasn't signed in, or can't sign in, then don't restore anything.
+        if (userName == null || !accountExistsOnDevice(userName)) {
+            boolean commitResult = sharedPrefs.edit().clear().commit();
+            Log.d(TAG, "onRestoreFinished complete, nothing restored; commit result = %s",
+                    commitResult);
+            return;
+        }
+
         SharedPreferences.Editor editor = sharedPrefs.edit();
         // Throw away prefs we don't want to restore.
         Set<String> restoredPrefs = new HashSet<>(Arrays.asList(RESTORED_ANDROID_PREFS));
         for (String pref : prefNames) {
-            Log.d(TAG, "Checking pref " + pref);
             if (!restoredPrefs.contains(pref)) editor.remove(pref);
         }
         // Because FirstRunSignInProcessor.FIRST_RUN_FLOW_SIGNIN_COMPLETE is not restored Chrome
         // will sign in the user on first run to the account in FIRST_RUN_FLOW_SIGNIN_ACCOUNT_NAME
         // if any. If the rest of FRE has been completed this will happen silently.
-        if (userName != null) {
-            editor.putString(FirstRunSignInProcessor.FIRST_RUN_FLOW_SIGNIN_ACCOUNT_NAME, userName);
-        }
+        editor.putString(FirstRunSignInProcessor.FIRST_RUN_FLOW_SIGNIN_ACCOUNT_NAME, userName);
         boolean commitResult = editor.commit();
 
-        Log.d(TAG, "onRestoreFinished complete; commit result = " + commitResult);
+        Log.d(TAG, "onRestoreFinished complete; commit result = %s", commitResult);
+    }
+
+    @VisibleForTesting
+    static void allowChromeApplicationForTesting() {
+        sAllowChromeApplication  = true;
     }
 }