Pass JavaRef to Java methods in android_webview.

android_webview/native/aw_pdf_exporter.h

Index: android_webview/native/aw_pdf_exporter.h
diff --git a/android_webview/native/aw_pdf_exporter.h b/android_webview/native/aw_pdf_exporter.h
index fd67b80800e676bbe75c236b82d959aee0fcbc36..aa08b5f67d6aa7ac62cd3bf88134a97fe15b74fd 100644
--- a/android_webview/native/aw_pdf_exporter.h
+++ b/android_webview/native/aw_pdf_exporter.h
@@ -24,7 +24,7 @@ namespace android_webview {
 class AwPdfExporter {
  public:
   AwPdfExporter(JNIEnv* env,
-                jobject obj,
+                const base::android::JavaRef<jobject>& obj,
                 content::WebContents* web_contents);
 
   ~AwPdfExporter();
@@ -36,7 +36,7 @@ class AwPdfExporter {
 
  private:
   void InitPdfSettings(JNIEnv* env,
-                       jobject obj,
+                       const base::android::JavaRef<jobject>& obj,
                        printing::PrintSettings& settings);
   void DidExportPdf(int fd, bool success);