Bug 1460874 - Part 1: Cleanups. r=geckoview-reviewers,snorp

The GeckoFontScaleListener is intended to live as long as the app (and there-
fore Gecko) remains alive and consequently keeps a reference to the
*application* context, so the linter warning can be safely suppressed.

Also reorder imports to match coding style.

Differential Revision: https://phabricator.services.mozilla.com/D17743

--HG--
extra : moz-landing-system : lando

mobile/android/base/java/org/mozilla/gecko/GeckoFontScaleListener.java

@@ -5,17 +5,18 @@
 
 package org.mozilla.gecko;
 
+import org.mozilla.gecko.preferences.GeckoPreferences;
+
+import android.annotation.SuppressLint;
 import android.content.ContentResolver;
 import android.content.Context;
-import android.database.ContentObserver;
 import android.content.SharedPreferences;
+import android.database.ContentObserver;
 import android.net.Uri;
 import android.provider.Settings;
 import android.support.annotation.UiThread;
 import android.util.Log;
 
-import org.mozilla.gecko.preferences.GeckoPreferences;
-
 class GeckoFontScaleListener
         extends ContentObserver
         implements SharedPreferences.OnSharedPreferenceChangeListener {
@@ -27,6 +28,8 @@ class GeckoFontScaleListener
     private static final int FONT_INFLATION_ON_DEFAULT_VALUE = 120;
     private static final float DEFAULT_FONT_SCALE = 1.0f;
 
+    // We're referencing the *application* context, so this is in fact okay.
+    @SuppressLint("StaticFieldLeak")
     private static final GeckoFontScaleListener listenerInstance = new GeckoFontScaleListener();
 
     private Context applicationContext;