Making OAuth2TokenService multi-login aware, updating callers, minor fixes

sync/android/java/src/org/chromium/sync/signin/AccountManagerHelper.java

Index: sync/android/java/src/org/chromium/sync/signin/AccountManagerHelper.java
diff --git a/sync/android/java/src/org/chromium/sync/signin/AccountManagerHelper.java b/sync/android/java/src/org/chromium/sync/signin/AccountManagerHelper.java
index 01ad1620bb73c38b9c0fc6954aab2c2f93bc5a38..1a6f34cfe983557a5acb88ff16e8aa190116905d 100644
--- a/sync/android/java/src/org/chromium/sync/signin/AccountManagerHelper.java
+++ b/sync/android/java/src/org/chromium/sync/signin/AccountManagerHelper.java
@@ -136,6 +136,13 @@ public class AccountManagerHelper {
     }
 
     /**
+     * Returns whether the accounts exists.
+     */
+    public boolean hasAccountForName(String accountName) {
+        return getAccountFromName(accountName) != null;
+    }
+
+    /**
      * @return Whether or not there is an account authenticator for Google accounts.
      */
     public boolean hasGoogleAccountAuthenticator() {