Move <webview> API to chrome layer

chrome/renderer/browser_plugin/chrome_webview_constants.h

+// Copyright (c) 2013 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.
+
+#ifndef  CHROME_RENDERER_BROWSER_PLUGIN_CHROME_WEBVIEW_CONSTANTS_H_
+#define  CHROME_RENDERER_BROWSER_PLUGIN_CHROME_WEBVIEW_CONSTANTS_H_
+
+namespace chrome {
+
+namespace webview {
+
+// Method bindings.
+extern const char kMethodBack[];
+extern const char kMethodForward[];
+extern const char kMethodGo[];
+extern const char kMethodReload[];
+extern const char kMethodStop[];
+
+}  // namespace webview
+
+}  // namespace chrome
+
+#endif  // CHROME_RENDERER_BROWSER_PLUGIN_CHROME_WEBVIEW_CONSTANTS_H_