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/cpptoc/resource_bundle_cpptoc.h

@@ -0,0 +1,35 @@
+// 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_CPPTOC_RESOURCE_BUNDLE_CPPTOC_H_
+#define CEF_LIBCEF_DLL_CPPTOC_RESOURCE_BUNDLE_CPPTOC_H_
+#pragma once
+
+#ifndef BUILDING_CEF_SHARED
+#pragma message("Warning: "__FILE__" may be accessed DLL-side only")
+#else  // BUILDING_CEF_SHARED
+
+#include "include/cef_resource_bundle.h"
+#include "include/capi/cef_resource_bundle_capi.h"
+#include "libcef_dll/cpptoc/cpptoc.h"
+
+// Wrap a C++ class with a C structure.
+// This class may be instantiated and accessed DLL-side only.
+class CefResourceBundleCppToC
+    : public CefCppToC<CefResourceBundleCppToC, CefResourceBundle,
+        cef_resource_bundle_t> {
+ public:
+  CefResourceBundleCppToC();
+};
+
+#endif  // BUILDING_CEF_SHARED
+#endif  // CEF_LIBCEF_DLL_CPPTOC_RESOURCE_BUNDLE_CPPTOC_H_