Change AccountManagerHelper initialization

components/signin/core/browser/android/java/src/org/chromium/components/signin/AccountManagerHelper.java

 // Copyright 2011 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.components.signin;
 
 import android.accounts.Account;
 import android.accounts.AuthenticatorDescription;
 import android.app.Activity;
-import android.content.Context;
 import android.os.AsyncTask;
 import android.support.annotation.Nullable;
 
 import org.chromium.base.Callback;
 import org.chromium.base.Log;
 import org.chromium.base.VisibleForTesting;
 import org.chromium.net.NetworkChangeNotifier;
 
 import java.util.ArrayList;
 import java.util.List;
@@ skipping 16 matching lines @@
     private static final String GOOGLEMAIL_COM = "googlemail.com";
     public static final String GOOGLE_ACCOUNT_TYPE = "com.google";
 
     /**
      * An account feature (corresponding to a Gaia service flag) that specifies whether the account
      * is a child account.
      */
     @VisibleForTesting
     public static final String FEATURE_IS_CHILD_ACCOUNT_KEY = "service_uca";
 
-    private static final AtomicReference<AccountManagerHelper> sInstance = new AtomicReference<>();
+    private static final AtomicReference<AccountManagerHelper> sAtomicInstance =
+            new AtomicReference<>();
+
+    private static final Object sLock = new Object();
+    private static Throwable sInstanceInitializedBy;
+    private static Throwable sTestingInstanceInitializedBy;
 
     private final AccountManagerDelegate mDelegate;
 
     /**
      * A simple callback for getAuthToken.
      */
     public interface GetAuthTokenCallback {
         /**
          * Invoked on the UI thread if a token is provided by the AccountManager.
          *
@@ skipping 11 matching lines @@
     }
 
     /**
      * @param delegate the account manager to use as a backend service
      */
     private AccountManagerHelper(AccountManagerDelegate delegate) {
         mDelegate = delegate;
     }
 
     /**
-     * Initialize AccountManagerHelper with a custom AccountManagerDelegate.
-     * Ensures that the singleton AccountManagerHelper hasn't been created yet.
-     * This can be overriden in tests using the overrideAccountManagerHelperForTests method.
+     * Initialize AccountManagerHelper with a custom AccountManagerDelegate. Ensures that it wasn't
+     * already initialized.
+     * Tests can override this, see {@link #overrideAccountManagerHelperForTests}.
+     *
+     * @param delegate the custom AccountManagerDelegate to use.
+     *
+     * @see #overrideAccountManagerHelperForTests
+     */
+    public static void initializeAccountManagerHelper(AccountManagerDelegate delegate) {
+        assert delegate != null;
+        synchronized (sLock) {
+            if (sInstanceInitializedBy != null) {
+                throw new IllegalStateException(
+                        "AccountManagerHelper is already initialized.", sInstanceInitializedBy);
+            }
+            sInstanceInitializedBy = new Throwable();
+            if (sTestingInstanceInitializedBy != null) return;
+            sAtomicInstance.set(new AccountManagerHelper(delegate));
+        }
+    }
+
+    /**
+     * Override AccountManagerHelper with a custom AccountManagerDelegate for tests. Only for use
+     * in tests. This should be called before call to {@link #initializeAccountManagerHelper}
+     * to make sure instance returned by {@link #get} doesn't change on the fly.
      *
      * @param delegate the custom AccountManagerDelegate to use.
      */
-    public static void initializeAccountManagerHelper(AccountManagerDelegate delegate) {
-        if (!sInstance.compareAndSet(null, new AccountManagerHelper(delegate))) {
-            throw new IllegalStateException("AccountManagerHelper is already initialized!");
+    @VisibleForTesting
+    public static void overrideAccountManagerHelperForTests(AccountManagerDelegate delegate) {
+        assert delegate != null;
+        synchronized (sLock) {
+            Throwable initializedBy = sInstanceInitializedBy != null
+                    ? sInstanceInitializedBy
+                    : sTestingInstanceInitializedBy;
+            if (initializedBy != null) {
+                throw new IllegalStateException(
+                        "AccountManagerHelper is already initialized.", initializedBy);
+            }
+            sTestingInstanceInitializedBy = new Throwable();
+            sAtomicInstance.set(new AccountManagerHelper(delegate));
         }
     }
 
     /**
      * Singleton instance getter. Singleton must be initialized before calling this
      * (by initializeAccountManagerHelper or overrideAccountManagerHelperForTests).
+     * It is guaranteed that this method always returns the same instance during app lifetime.
      *
      * @return a singleton instance
      */
     public static AccountManagerHelper get() {
-        AccountManagerHelper instance = sInstance.get();
+        AccountManagerHelper instance = sAtomicInstance.get();
         assert instance != null : "AccountManagerHelper is not initialized!";
         return instance;
     }
 
     /**
-     * Override AccountManagerHelper with a custom AccountManagerDelegate in tests.
-     * Unlike initializeAccountManagerHelper, this will override the existing instance of
-     * AccountManagerHelper if any. Only for use in Tests.
-     *
-     * @param context the applicationContext is retrieved from the context used as an argument.
-     * @param delegate the custom AccountManagerDelegate to use.
-     */
-    @VisibleForTesting
-    public static void overrideAccountManagerHelperForTests(
-            Context context, AccountManagerDelegate delegate) {
-        sInstance.set(new AccountManagerHelper(delegate));
-    }
-
-    /**
-     * Resets custom AccountManagerHelper set with {@link #overrideAccountManagerHelperForTests}.
-     * Only for use in Tests.
-     */
-    @VisibleForTesting
-    public static void resetAccountManagerHelperForTests() {
-        sInstance.set(null);
-    }
-
-    /**
      * Creates an Account object for the given name.
      */
     public static Account createAccountFromName(String name) {
         return new Account(name, GOOGLE_ACCOUNT_TYPE);
     }
 
     /**
      * This method is deprecated; please use the asynchronous version below instead.
      *
      * See http://crbug.com/517697 for details.
@@ skipping 311 matching lines @@
         public void onConnectionTypeChanged(int connectionType) {
             assert mNumTries.get() < MAX_TRIES;
             if (NetworkChangeNotifier.isOnline()) {
                 // The network is back; stop listening and try again.
                 NetworkChangeNotifier.removeConnectionTypeObserver(this);
                 attempt();
             }
         }
     }
 }