jni: Pass method parameters as JavaParamRef in content.

content/browser/time_zone_monitor_android.h

 // Copyright 2014 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 CONTENT_BROWSER_TIME_ZONE_MONITOR_ANDROID_H_
 #define CONTENT_BROWSER_TIME_ZONE_MONITOR_ANDROID_H_
 
 #include "content/browser/time_zone_monitor.h"
 
 #include <jni.h>
 
 #include "base/android/scoped_java_ref.h"
 #include "base/basictypes.h"
 
 namespace content {
 
 class TimeZoneMonitorAndroid : public TimeZoneMonitor {
  public:
   TimeZoneMonitorAndroid();
   ~TimeZoneMonitorAndroid() override;
 
   // Must be called at startup.
   static bool Register(JNIEnv* env);
 
   // Called by the Java implementation when the system time zone changes.
-  void TimeZoneChangedFromJava(JNIEnv* env, jobject caller);
+  void TimeZoneChangedFromJava(
+      JNIEnv* env,
+      const base::android::JavaParamRef<jobject>& caller);
 
  private:
   // Java provider of system time zone change notifications.
   base::android::ScopedJavaGlobalRef<jobject> impl_;
 
   DISALLOW_COPY_AND_ASSIGN(TimeZoneMonitorAndroid);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_TIME_ZONE_MONITOR_ANDROID_H_