Bug 1407835 - Don't keep BrowserApp unnecessarily alive through sScreenOrientationDelegate. r=nalexander

We need to clear the reference again if BrowserApp is possibly going to be destroyed.

At the moment there aren't any other activities using setScreenOrientationDelegate, but in preparation for that happening we unset BrowserApp as delegate already in onPause (instead of onDestroy) so we don't mistakenly assume that BrowserApp will remain the active ScreenOrientationDelegate all the time, even when it has been paused by some other activity.

MozReview-Commit-ID: 9q0MSzi78Vm

--HG--
extra : rebase_source : e5e1550d0d76fc21e36865489a3f3809f64468bf

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

@@ -2136,6 +2136,8 @@ public abstract class GeckoApp extends GeckoActivity
             }
         });
 
+        GeckoAppShell.setScreenOrientationDelegate(null);
+
         super.onPause();
     }
 

mobile/android/geckoview/src/main/java/org/mozilla/gecko/GeckoAppShell.java

@@ -84,6 +84,7 @@ import android.os.SystemClock;
 import android.os.Vibrator;
 import android.provider.Settings;
 import android.support.annotation.NonNull;
+import android.support.annotation.Nullable;
 import android.support.v4.util.SimpleArrayMap;
 import android.telephony.TelephonyManager;
 import android.text.TextUtils;
@@ -628,7 +629,7 @@ public class GeckoAppShell
         return sScreenOrientationDelegate;
     }
 
-    public static void setScreenOrientationDelegate(ScreenOrientationDelegate screenOrientationDelegate) {
+    public static void setScreenOrientationDelegate(@Nullable ScreenOrientationDelegate screenOrientationDelegate) {
         sScreenOrientationDelegate = (screenOrientationDelegate != null) ? screenOrientationDelegate : DEFAULT_LISTENERS;
     }