jni: Pass method parameters as JavaParamRef in printing.

printing/printing_context_android.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 PRINTING_PRINTING_CONTEXT_ANDROID_H_
 #define PRINTING_PRINTING_CONTEXT_ANDROID_H_
 
 #include <jni.h>
 
 #include <string>
 
 #include "base/android/scoped_java_ref.h"
 #include "printing/printing_context.h"
 
 namespace printing {
 
 // Android subclass of PrintingContext. This class communicates with the
 // Java side through JNI.
 class PRINTING_EXPORT PrintingContextAndroid : public PrintingContext {
  public:
   explicit PrintingContextAndroid(Delegate* delegate);
   ~PrintingContextAndroid() override;
 
   // Called when the page is successfully written to a PDF using the file
   // descriptor specified, or when the printing operation failed.
   static void PdfWritingDone(int fd, bool success);
 
   // Called from Java, when printing settings from the user are ready or the
   // printing operation is canceled.
-  void AskUserForSettingsReply(JNIEnv* env, jobject obj, jboolean success);
+  void AskUserForSettingsReply(JNIEnv* env,
+                               const base::android::JavaParamRef<jobject>& obj,
+                               jboolean success);
 
   // Called from Java, when a printing process initiated by a script finishes.
-  void ShowSystemDialogDone(JNIEnv* env, jobject obj);
+  void ShowSystemDialogDone(JNIEnv* env,
+                            const base::android::JavaParamRef<jobject>& obj);
 
   // PrintingContext implementation.
   void AskUserForSettings(int max_pages,
                           bool has_selection,
                           bool is_scripted,
                           const PrintSettingsCallback& callback) override;
   Result UseDefaultSettings() override;
   gfx::Size GetPdfPaperSizeDeviceUnits() override;
   Result UpdatePrinterSettings(bool external_preview,
                                bool show_system_dialog,
@@ skipping 17 matching lines @@
   // ready on the Java side
   PrintSettingsCallback callback_;
 
   DISALLOW_COPY_AND_ASSIGN(PrintingContextAndroid);
 };
 
 }  // namespace printing
 
 #endif  // PRINTING_PRINTING_CONTEXT_ANDROID_H_