Remove AccountManagerDelegate.removeAccount()

This method was unused and causing a deprecation warning.

BUG=486200

Review URL: https://codereview.chromium.org/1139783003

Cr-Commit-Position: refs/heads/master@{#329668}

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

@@ -37,9 +37,6 @@ public interface AccountManagerDelegate {
 
     boolean addAccountExplicitly(Account account, String password, Bundle userdata);
 
-    AccountManagerFuture<Boolean> removeAccount(Account account,
-            AccountManagerCallback<Boolean> callback, Handler handler);
-
     String getPassword(Account account);
 
     void setPassword(Account account, String password);

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

@@ -72,12 +72,6 @@ public class SystemAccountManagerDelegate implements AccountManagerDelegate {
         return mAccountManager.addAccountExplicitly(account, password, userdata);
     }
 
-    @Override
-    public AccountManagerFuture<Boolean> removeAccount(Account account,
-            AccountManagerCallback<Boolean> callback, Handler handler) {
-        return mAccountManager.removeAccount(account, callback, handler);
-    }
-
     @Override
     public String getPassword(Account account) {
         return mAccountManager.getPassword(account);

sync/test/android/javatests/src/org/chromium/sync/test/util/MockAccountManager.java

@@ -158,21 +158,6 @@ public class MockAccountManager implements AccountManagerDelegate {
         return result;
     }
 
-    @Override
-    public AccountManagerFuture<Boolean> removeAccount(Account account,
-            AccountManagerCallback<Boolean> callback, Handler handler) {
-        mAccounts.remove(getAccountHolder(account));
-        postAsyncAccountChangedEvent();
-        return runTask(mExecutor,
-                new AccountManagerTask<Boolean>(handler, callback, new Callable<Boolean>() {
-                    @Override
-                    public Boolean call() throws Exception {
-                        // Removal always successful.
-                        return true;
-                    }
-                }));
-    }
-
     @Override
     public String getPassword(Account account) {
         return getAccountHolder(account).getPassword();