Add plugin placeholder and policy support (issue #1708)

- Default plugin loading policy can be specified using the new
  `--plugin-policy=[allow|block|detect]` command-line flag.
- Move CefRequestHandler::OnBeforePluginLoad to
  CefRequestContextHandler and add a new policy argument that
  supports different actions (allow, block, detect, disable) on a
  per-plugin-instance basis.
- Add CefContextMenuHandler::RunContextMenu for providing a custom
  context menu implementation.
- Add CefResourceBundleHandler::GetDataResourceForScale for
  returning scaled resources (issue #1272).
- Add CefResourceBundle for retrieving resources from the resource
  bundle (*.pak) files loaded by CEF during startup or via the
  CefResourceBundleHandler.
- Linux: Fix Debug build IO access warning with CefGetMimeType.
- cef_unittests: Move the refcounting implementation from TestHandler
  to subclasses in order to support interface inheritance from
  subclasses.

libcef_dll/ctocpp/run_context_menu_callback_ctocpp.h

@@ -0,0 +1,39 @@
+// Copyright (c) 2015 The Chromium Embedded Framework Authors. All rights
+// reserved. Use of this source code is governed by a BSD-style license that
+// can be found in the LICENSE file.
+//
+// ---------------------------------------------------------------------------
+//
+// This file was generated by the CEF translator tool. If making changes by
+// hand only do so within the body of existing method and function
+// implementations. See the translator.README.txt file in the tools directory
+// for more information.
+//
+
+#ifndef CEF_LIBCEF_DLL_CTOCPP_RUN_CONTEXT_MENU_CALLBACK_CTOCPP_H_
+#define CEF_LIBCEF_DLL_CTOCPP_RUN_CONTEXT_MENU_CALLBACK_CTOCPP_H_
+#pragma once
+
+#ifndef USING_CEF_SHARED
+#pragma message("Warning: "__FILE__" may be accessed wrapper-side only")
+#else  // USING_CEF_SHARED
+
+#include "include/cef_context_menu_handler.h"
+#include "include/capi/cef_context_menu_handler_capi.h"
+#include "libcef_dll/ctocpp/ctocpp.h"
+
+// Wrap a C structure with a C++ class.
+// This class may be instantiated and accessed wrapper-side only.
+class CefRunContextMenuCallbackCToCpp
+    : public CefCToCpp<CefRunContextMenuCallbackCToCpp,
+        CefRunContextMenuCallback, cef_run_context_menu_callback_t> {
+ public:
+  CefRunContextMenuCallbackCToCpp();
+
+  // CefRunContextMenuCallback methods.
+  void Continue(int command_id, EventFlags event_flags) OVERRIDE;
+  void Cancel() OVERRIDE;
+};
+
+#endif  // USING_CEF_SHARED
+#endif  // CEF_LIBCEF_DLL_CTOCPP_RUN_CONTEXT_MENU_CALLBACK_CTOCPP_H_