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/run_context_menu_callback_cpptoc.cc

@@ -0,0 +1,72 @@
+// 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.
+//
+
+#include "libcef_dll/cpptoc/run_context_menu_callback_cpptoc.h"
+
+
+namespace {
+
+// MEMBER FUNCTIONS - Body may be edited by hand.
+
+void CEF_CALLBACK run_context_menu_callback_cont(
+    struct _cef_run_context_menu_callback_t* self, int command_id,
+    cef_event_flags_t event_flags) {
+  // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
+
+  DCHECK(self);
+  if (!self)
+    return;
+
+  // Execute
+  CefRunContextMenuCallbackCppToC::Get(self)->Continue(
+      command_id,
+      event_flags);
+}
+
+void CEF_CALLBACK run_context_menu_callback_cancel(
+    struct _cef_run_context_menu_callback_t* self) {
+  // AUTO-GENERATED CONTENT - DELETE THIS COMMENT BEFORE MODIFYING
+
+  DCHECK(self);
+  if (!self)
+    return;
+
+  // Execute
+  CefRunContextMenuCallbackCppToC::Get(self)->Cancel();
+}
+
+}  // namespace
+
+
+// CONSTRUCTOR - Do not edit by hand.
+
+CefRunContextMenuCallbackCppToC::CefRunContextMenuCallbackCppToC() {
+  GetStruct()->cont = run_context_menu_callback_cont;
+  GetStruct()->cancel = run_context_menu_callback_cancel;
+}
+
+template<> CefRefPtr<CefRunContextMenuCallback> CefCppToC<CefRunContextMenuCallbackCppToC,
+    CefRunContextMenuCallback, cef_run_context_menu_callback_t>::UnwrapDerived(
+    CefWrapperType type, cef_run_context_menu_callback_t* s) {
+  NOTREACHED() << "Unexpected class type: " << type;
+  return NULL;
+}
+
+#ifndef NDEBUG
+template<> base::AtomicRefCount CefCppToC<CefRunContextMenuCallbackCppToC,
+    CefRunContextMenuCallback, cef_run_context_menu_callback_t>::DebugObjCt =
+    0;
+#endif
+
+template<> CefWrapperType CefCppToC<CefRunContextMenuCallbackCppToC,
+    CefRunContextMenuCallback, cef_run_context_menu_callback_t>::kWrapperType =
+    WT_RUN_CONTEXT_MENU_CALLBACK;