Move allocate instance id to chrome/.

chrome/browser/extensions/api/guestview/guestview_api.cc

+// Copyright 2014 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/guestview/guestview_api.h"
+
+#include "chrome/browser/guest_view/guest_view_manager.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/common/extensions/api/guestview.h"
+
+namespace guestview = extensions::api::guestview;
+
+namespace extensions {
+
+GuestviewAllocateInstanceIdFunction::GuestviewAllocateInstanceIdFunction() {
+}
+
+bool GuestviewAllocateInstanceIdFunction::RunAsync() {
+  EXTENSION_FUNCTION_VALIDATE(!args_->GetSize());
+
+  // Check if we have "webview" permission.
+  CHECK(GetExtension()->HasAPIPermission(APIPermission::kWebView));
+
+  int instanceId =
+      GuestViewManager::FromBrowserContext(
+          browser_context())->GetNextInstanceID();
+  SetResult(base::Value::CreateIntegerValue(instanceId));
+  SendResponse(true);
+  return true;
+}
+
+}  // namespace extensions