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 155 matching lines @@
         nativeSetForceEnableZoom(mFontSizePrefsAndroidPtr, enabled);
     }
 
     public boolean getForceEnableZoom() {
         return nativeGetForceEnableZoom(mFontSizePrefsAndroidPtr);
     }
 
     public void destroy() {
         mSharedPreferences.unregisterOnSharedPreferenceChangeListener(this);
         nativeDestroy(mFontSizePrefsAndroidPtr);
+        mObserverMap.clear();

[Ted C, 2014/09/15 18:42:37]

destroy seems like an odd API to have on a singleton.  The singleton would now
be in an invalid state and can never be reused.  That isn't a comment about this
change per say, but it's just general confusion about this.

Now for this, are the observers being cleaned up as part of the native destroy
call?  To me, it looks like this could end up leaking the native observer
references.  If that is the case, we should be iterating over the map and
calling destroy on them to make sure that doesn't happen.

Also, I can't find any references to this method and I suspect it is never
actually called (nor does it really need to as destroy would only come when
android is about to destroy our application and kill the process).

[nyquist, 2014/09/15 19:56:50]

Yes, .clear() would be wrong. I think it would be better to just remove this
method alltogether.

[wajahat, 2014/09/16 09:30:36]

As this is a singleton class and there are no references to destroy() hence
removing this method altogether.

On 2014/09/15 18:42:37, Ted C wrote:

[wajahat, 2014/09/16 09:30:36]

Done.

     }
 
     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);
 }