Support registration of custom preferences.

Custom global and request context preferences can now be registered via
CefBrowserProcessHandler::OnRegisterCustomPreferences. CefRequestContext
now extends CefPreferenceManager and global preferences can be accessed
via CefPreferenceManager::GetGlobalPreferenceManager.

libcef_dll/ctocpp/preference_manager_ctocpp.h

@@ -0,0 +1,48 @@
+// Copyright (c) 2022 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.
+//
+// $hash=ec2addea82a8ad9018bd3f8e8dee80c998c7229b$
+//
+
+#ifndef CEF_LIBCEF_DLL_CTOCPP_PREFERENCE_MANAGER_CTOCPP_H_
+#define CEF_LIBCEF_DLL_CTOCPP_PREFERENCE_MANAGER_CTOCPP_H_
+#pragma once
+
+#if !defined(WRAPPING_CEF_SHARED)
+#error This file can be included wrapper-side only
+#endif
+
+#include "include/capi/cef_preference_capi.h"
+#include "include/cef_preference.h"
+#include "libcef_dll/ctocpp/ctocpp_ref_counted.h"
+
+// Wrap a C structure with a C++ class.
+// This class may be instantiated and accessed wrapper-side only.
+class CefPreferenceManagerCToCpp
+    : public CefCToCppRefCounted<CefPreferenceManagerCToCpp,
+                                 CefPreferenceManager,
+                                 cef_preference_manager_t> {
+ public:
+  CefPreferenceManagerCToCpp();
+  virtual ~CefPreferenceManagerCToCpp();
+
+  // CefPreferenceManager methods.
+  bool HasPreference(const CefString& name) override;
+  CefRefPtr<CefValue> GetPreference(const CefString& name) override;
+  CefRefPtr<CefDictionaryValue> GetAllPreferences(
+      bool include_defaults) override;
+  bool CanSetPreference(const CefString& name) override;
+  bool SetPreference(const CefString& name,
+                     CefRefPtr<CefValue> value,
+                     CefString& error) override;
+};
+
+#endif  // CEF_LIBCEF_DLL_CTOCPP_PREFERENCE_MANAGER_CTOCPP_H_