Revert of Remove NPAPI plugin from chromoting webapp.

remoting/host/plugin/host_log_handler.h

+// Copyright (c) 2011 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 REMOTING_HOST_PLUGIN_HOST_LOG_HANDLER_H_
+#define REMOTING_HOST_PLUGIN_HOST_LOG_HANDLER_H_
+
+#include <string>
+
+namespace remoting {
+
+class HostNPScriptObject;
+
+class HostLogHandler {
+ public:
+  // Register the log handler.
+  // These should be called from the plugin init/destroy methods so that they
+  // are only called once per plugin process (not once per plugin instance).
+  static void RegisterLogMessageHandler();
+
+  // We don't have the corresponding UnregisterLogMessageHandler because it
+  // is not safe to call it when there are multiple threads that might be
+  // logging.
+
+  static void RegisterLoggingScriptObject(HostNPScriptObject* script_object);
+  static void UnregisterLoggingScriptObject(HostNPScriptObject* script_object);
+
+ private:
+  // A Log Message Handler that is called after each LOG message has been
+  // processed. This must be of type LogMessageHandlerFunction defined in
+  // base/logging.h.
+  static bool LogToUI(int severity, const char* file, int line,
+                      size_t message_start, const std::string& str);
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_PLUGIN_HOST_LOG_HANDLER_H_