Pass method parameters as JavaParamRef in android_webview.

android_webview/native/aw_pdf_exporter.h

 // Copyright 2013 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 ANDROID_WEBVIEW_NATIVE_AW_PDF_EXPORTER_H_
 #define ANDROID_WEBVIEW_NATIVE_AW_PDF_EXPORTER_H_
 
 #include <jni.h>
 
 #include "base/android/jni_weak_ref.h"
@@ skipping 13 matching lines @@
 
 class AwPdfExporter {
  public:
   AwPdfExporter(JNIEnv* env,
                 jobject obj,
                 content::WebContents* web_contents);
 
   ~AwPdfExporter();
 
   void ExportToPdf(JNIEnv* env,
-                   jobject obj,
+                   const base::android::JavaParamRef<jobject>& obj,
                    int fd,
-                   jobject cancel_signal);
+                   const base::android::JavaParamRef<jobject>& cancel_signal);
 
  private:
   void InitPdfSettings(JNIEnv* env,
                        jobject obj,
                        printing::PrintSettings& settings);
   void DidExportPdf(int fd, bool success);
 
   JavaObjectWeakGlobalRef java_ref_;
   content::WebContents* web_contents_;
 
   DISALLOW_COPY_AND_ASSIGN(AwPdfExporter);
 };
 
 bool RegisterAwPdfExporter(JNIEnv* env);
 
 }  // namespace android_webview
 
 #endif  // ANDROID_WEBVIEW_NATIVE_AW_PDF_EXPORTER_H_