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

chrome/android/java/src/org/chromium/chrome/browser/accessibility/FontSizePrefs.java

 // 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.
 
 package org.chromium.chrome.browser.accessibility;
 
 import android.content.Context;
 import android.content.SharedPreferences;
 import android.content.SharedPreferences.OnSharedPreferenceChangeListener;
 import android.preference.PreferenceManager;
@@ skipping 152 matching lines @@
     }
 
     public void setForceEnableZoom(boolean enabled) {
         nativeSetForceEnableZoom(mFontSizePrefsAndroidPtr, enabled);
     }
 
     public boolean getForceEnableZoom() {
         return nativeGetForceEnableZoom(mFontSizePrefsAndroidPtr);
     }
 
-    public void destroy() {
-        mSharedPreferences.unregisterOnSharedPreferenceChangeListener(this);
-        nativeDestroy(mFontSizePrefsAndroidPtr);
-    }
-
     private native void nativeAddObserver(long nativeFontSizePrefsAndroid,
             long nativeObserverPtr);
 
     private native void nativeRemoveObserver(long nativeFontSizePrefsAndroid,
             long nativeObserverPtr);
 
     private native long nativeInit();
 
-    private native void nativeDestroy(long nativeFontSizePrefsAndroid);
-
     private native void nativeSetFontScaleFactor(long nativeFontSizePrefsAndroid, float font);
 
     private native float nativeGetFontScaleFactor(long nativeFontSizePrefsAndroid);
 
     private native boolean nativeGetForceEnableZoom(long nativeFontSizePrefsAndroid);
 
     private native void nativeSetForceEnableZoom(long nativeFontSizePrefsAndroid, boolean enabled);
 }