Fix for actionbar 'up' fix when rotating

We seem to lose the mediaDetails fragment when we change state. Noooooo!

Author: bvibber

commons/src/main/java/org/wikimedia/commons/contributions/ContributionsActivity.java

@@ -103,10 +103,25 @@ protected void onCreate(Bundle savedInstanceState) {
         contributionsList = (ContributionsListFragment)getSupportFragmentManager().findFragmentById(R.id.contributionsListFragment);
 
         getSupportFragmentManager().addOnBackStackChangedListener(this);
+        if (savedInstanceState != null) {
+            mediaDetails = (MediaDetailPagerFragment)getSupportFragmentManager().findFragmentById(R.id.contributionsFragmentContainer);
+            // onBackStackChanged uses mediaDetails.isVisible() but this returns false now.
+            // Use the saved value from before pause or orientation change.
+            if (mediaDetails != null && savedInstanceState.getBoolean("mediaDetailsVisible")) {
+                // Feels awful that we have to reset this manually!
+                getSupportActionBar().setDisplayHomeAsUpEnabled(true);
+            }
+        }
 
         requestAuthToken();
     }
 
+    @Override
+    protected void onSaveInstanceState(Bundle outState) {
+        super.onSaveInstanceState(outState);
+        outState.putBoolean("mediaDetailsVisible", (mediaDetails != null && mediaDetails.isVisible()));
+    }
+
     private void showDetail(int i) {
         if(mediaDetails == null ||!mediaDetails.isVisible()) {
             mediaDetails = new MediaDetailPagerFragment();