Move impl of identity.GetAccounts() extension API to its own file

chrome/browser/extensions/api/identity/identity_get_accounts_function.cc

+// Copyright 2017 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.
+
+#include "chrome/browser/extensions/api/identity/identity_get_accounts_function.h"
+
+#include "chrome/browser/extensions/api/identity/identity_api.h"
+#include "chrome/browser/extensions/api/identity/identity_constants.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/common/extensions/api/identity.h"
+#include "components/signin/core/common/profile_management_switches.h"
+
+namespace extensions {
+
+IdentityGetAccountsFunction::IdentityGetAccountsFunction() {
+}
+
+IdentityGetAccountsFunction::~IdentityGetAccountsFunction() {
+}
+
+ExtensionFunction::ResponseAction IdentityGetAccountsFunction::Run() {
+  if (GetProfile()->IsOffTheRecord()) {
+    return RespondNow(Error(identity_constants::kOffTheRecord));
+  }
+
+  std::vector<std::string> gaia_ids =
+      IdentityAPI::GetFactoryInstance()->Get(GetProfile())->GetAccounts();
+  DCHECK(gaia_ids.size() < 2 || switches::IsExtensionsMultiAccount());
+
+  std::unique_ptr<base::ListValue> infos(new base::ListValue());
+
+  for (std::vector<std::string>::const_iterator it = gaia_ids.begin();
+       it != gaia_ids.end();
+       ++it) {
+    api::identity::AccountInfo account_info;
+    account_info.id = *it;
+    infos->Append(account_info.ToValue());
+  }
+
+  return RespondNow(OneArgument(std::move(infos)));
+}
+
+}  // namespace extensions