Revert of Reimplement AccountManagerHelper singleton instance creation

chrome/android/javatests/src/org/chromium/chrome/browser/signin/OAuth2TokenServiceIntegrationTest.java

Index: chrome/android/javatests/src/org/chromium/chrome/browser/signin/OAuth2TokenServiceIntegrationTest.java
diff --git a/chrome/android/javatests/src/org/chromium/chrome/browser/signin/OAuth2TokenServiceIntegrationTest.java b/chrome/android/javatests/src/org/chromium/chrome/browser/signin/OAuth2TokenServiceIntegrationTest.java
index 2d97c009be287da069f12ce9c65f3f68fd7d4c61..8500c46bc7e0d3a9d7baa0f3eab0f83c4628c914 100644
--- a/chrome/android/javatests/src/org/chromium/chrome/browser/signin/OAuth2TokenServiceIntegrationTest.java
+++ b/chrome/android/javatests/src/org/chromium/chrome/browser/signin/OAuth2TokenServiceIntegrationTest.java
@@ -65,17 +65,15 @@
         mapAccountNamesToIds();
         ApplicationData.clearAppData(
                 InstrumentationRegistry.getInstrumentation().getTargetContext());
-
-        // loadNativeLibraryAndInitBrowserProcess will access AccountManagerHelper, so it should
-        // be initialized beforehand.
+        mActivityTestRule.loadNativeLibraryAndInitBrowserProcess();
+
+        // Set up AccountManager.
         mContext = new AdvancedMockContext(
                 InstrumentationRegistry.getInstrumentation().getTargetContext());
         mAccountManager = new MockAccountManager(
                 mContext, InstrumentationRegistry.getInstrumentation().getContext());
         AccountManagerHelper.overrideAccountManagerHelperForTests(mContext, mAccountManager);
 
-        mActivityTestRule.loadNativeLibraryAndInitBrowserProcess();
-
         // Make sure there is no account signed in yet.
         mChromeSigninController = ChromeSigninController.get();
         mChromeSigninController.setSignedInAccountName(null);
@@ -100,7 +98,6 @@
                 mOAuth2TokenService.validateAccounts(false);
             }
         });
-        AccountManagerHelper.resetAccountManagerHelperForTests();
     }
 
     private void mapAccountNamesToIds() {