Convert SetIsIncognitoProcess to use mojo.

chrome/common/renderer.mojom

+// Copyright 2016 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.
+
+module chrome.mojom;
+
+// The primordial Channel-associated interface implemented by a render process.
+// This should be used for implementing browser-to-renderer control messages
+// which need to retain FIFO with respect to legacy IPC messages.
+interface Renderer {
+  // Configures the renderer, queued to send when the render process will
+  // launch.
+  //
+  // TODO(nigeltao): port the ChromeViewMsg_SetContentSettingRules legacy IPC
+  // message to be an additional arg here.
+  SetInitialConfiguration(bool is_incognito_process);
+};