Remove FontSizePrefs destroy() method as its a singleton class.

chrome/browser/android/accessibility/font_size_prefs_android.cc

 // 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.
 
 #include "chrome/browser/android/accessibility/font_size_prefs_android.h"
 
 #include "base/observer_list.h"
 #include "base/prefs/pref_change_registrar.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/profiles/profile_android.h"
@@ skipping 12 matching lines @@
                  base::Unretained(this)));
   pref_change_registrar_->Add(
       prefs::kWebKitForceEnableZoom,
       base::Bind(&FontSizePrefsAndroid::OnForceEnableZoomPrefsChanged,
                  base::Unretained(this)));
 }
 
 FontSizePrefsAndroid::~FontSizePrefsAndroid() {
 }
 
-void FontSizePrefsAndroid::Destroy(JNIEnv* env, jobject obj) {
-  delete this;
-}
-
 void FontSizePrefsAndroid::SetFontScaleFactor(JNIEnv* env,
                                               jobject obj,
                                               jfloat font_size) {
   pref_service_->SetDouble(prefs::kWebKitFontScaleFactor,
                            static_cast<double>(font_size));
 }
 
 float FontSizePrefsAndroid::GetFontScaleFactor(JNIEnv* env, jobject obj) {
   return pref_service_->GetDouble(prefs::kWebKitFontScaleFactor);
 }
@@ skipping 76 matching lines @@
   JNIEnv* env = base::android::AttachCurrentThread();
   Java_FontSizePrefsObserverWrapper_onChangeFontSize(
       env, java_ref_.obj(), font_size);
 }
 
 void FontSizePrefsObserverAndroid::OnChangeForceEnableZoom(bool enabled) {
   JNIEnv* env = base::android::AttachCurrentThread();
   Java_FontSizePrefsObserverWrapper_onChangeForceEnableZoom(
       env, java_ref_.obj(), enabled);
 }