Bug 1056225 - Part 2: Lift onConfigurationChanged to HomeFragment. r=margaret

I took the most commented version.  There are two things to note here:

* Several panels did not define onConfigurationChanged.  It's not clear
  if these panels didn't need it (after some analysis?) or if they just
  didn't copy-paste thoroughly.  This version is always safe, if
  inefficient, and I've commented to say as much.

* The order of operations for the Bookmarks panel may be delicate.  I
  did not preserve the original order (save stack first, then detach and
  attach); it appears to not be necessary to save the stack first,
  because the configuration change is completed before the containing
  Activity is restarted (and the stack is restored).  I tested that the
  folder stack was preserved across device rotations locally.

mobile/android/base/home/BookmarksPanel.java

@@ -140,23 +140,10 @@ public class BookmarksPanel extends HomeFragment {
     public void onConfigurationChanged(Configuration newConfig) {
         super.onConfigurationChanged(newConfig);
 
-        // Reattach the fragment, forcing a reinflation of its view.
-        // We use commitAllowingStateLoss() instead of commit() here to avoid
-        // an IllegalStateException. If the phone is rotated while Fennec
-        // is in the background, onConfigurationChanged() is fired.
-        // onConfigurationChanged() is called before onResume(), so
-        // using commit() would throw an IllegalStateException since it can't
-        // be used between the Activity's onSaveInstanceState() and
-        // onResume().
         if (isVisible()) {
             // The parent stack is saved just so that the folder state can be
             // restored on rotation.
             mSavedParentStack = mListAdapter.getParentStack();
-
-            getFragmentManager().beginTransaction()
-                                .detach(this)
-                                .attach(this)
-                                .commitAllowingStateLoss();
         }
     }
 

mobile/android/base/home/DynamicPanel.java

@@ -16,7 +16,6 @@ import org.mozilla.gecko.util.UiAsyncTask;
 
 import android.content.ContentResolver;
 import android.content.Context;
-import android.content.res.Configuration;
 import android.database.Cursor;
 import android.net.Uri;
 import android.os.Bundle;
@@ -143,19 +142,6 @@ public class DynamicPanel extends HomeFragment {
         }
     }
 
-    @Override
-    public void onConfigurationChanged(Configuration newConfig) {
-        super.onConfigurationChanged(newConfig);
-
-        // Detach and reattach the fragment as the layout changes.
-        if (isVisible()) {
-            getFragmentManager().beginTransaction()
-                                .detach(this)
-                                .attach(this)
-                                .commitAllowingStateLoss();
-        }
-    }
-
     @Override
     public void onActivityCreated(Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);

mobile/android/base/home/HomeFragment.java

@@ -272,9 +272,35 @@ abstract class HomeFragment extends Fragment {
         loadIfVisible();
     }
 
+    /**
+     * Handle a configuration change by detaching and re-attaching.
+     * <p>
+     * A HomeFragment only needs to handle onConfiguration change (i.e.,
+     * re-attach) if its UI needs to change (i.e., re-inflate layouts, use
+     * different styles, etc) for different device orientations. Handling
+     * configuration changes in all HomeFragments will simply cause some
+     * redundant re-inflations on device rotation. This slight inefficiency
+     * avoids potentially not handling a needed onConfigurationChanged in a
+     * subclass.
+     */
     @Override
     public void onConfigurationChanged(Configuration newConfig) {
         super.onConfigurationChanged(newConfig);
+
+        // Reattach the fragment, forcing a re-inflation of its view.
+        // We use commitAllowingStateLoss() instead of commit() here to avoid
+        // an IllegalStateException. If the phone is rotated while Fennec
+        // is in the background, onConfigurationChanged() is fired.
+        // onConfigurationChanged() is called before onResume(), so
+        // using commit() would throw an IllegalStateException since it can't
+        // be used between the Activity's onSaveInstanceState() and
+        // onResume().
+        if (isVisible()) {
+            getFragmentManager().beginTransaction()
+                                .detach(this)
+                                .attach(this)
+                                .commitAllowingStateLoss();
+        }
     }
 
     void setCanLoadHint(boolean canLoadHint) {

mobile/android/base/home/ReadingListPanel.java

@@ -17,7 +17,6 @@ import org.mozilla.gecko.db.BrowserDB;
 import org.mozilla.gecko.home.HomePager.OnUrlOpenListener;
 
 import android.content.Context;
-import android.content.res.Configuration;
 import android.database.Cursor;
 import android.os.Bundle;
 import android.support.v4.app.LoaderManager.LoaderCallbacks;
@@ -112,19 +111,6 @@ public class ReadingListPanel extends HomeFragment {
         mEmptyView = null;
     }
 
-    @Override
-    public void onConfigurationChanged(Configuration newConfig) {
-        super.onConfigurationChanged(newConfig);
-
-        // Detach and reattach the fragment as the layout changes.
-        if (isVisible()) {
-            getFragmentManager().beginTransaction()
-                                .detach(this)
-                                .attach(this)
-                                .commitAllowingStateLoss();
-        }
-    }
-
     @Override
     public void onActivityCreated(Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);

mobile/android/base/home/RecentTabsPanel.java

@@ -27,7 +27,6 @@ import org.mozilla.gecko.util.ThreadUtils;
 
 import android.app.Activity;
 import android.content.Context;
-import android.content.res.Configuration;
 import android.database.Cursor;
 import android.database.MatrixCursor;
 import android.database.MatrixCursor.RowBuilder;
@@ -48,6 +47,7 @@ import android.widget.TextView;
 public class RecentTabsPanel extends HomeFragment
                              implements NativeEventListener {
     // Logging tag name
+    @SuppressWarnings("unused")
     private static final String LOGTAG = "GeckoRecentTabsPanel";
 
     // Cursor loader ID for the loader that loads recent tabs
@@ -181,19 +181,6 @@ public class RecentTabsPanel extends HomeFragment
         GeckoAppShell.sendEventToGecko(GeckoEvent.createBroadcastEvent("ClosedTabs:StopNotifications", null));
     }
 
-    @Override
-    public void onConfigurationChanged(Configuration newConfig) {
-        super.onConfigurationChanged(newConfig);
-
-        // Detach and reattach the fragment as the layout changes.
-        if (isVisible()) {
-            getFragmentManager().beginTransaction()
-                                .detach(this)
-                                .attach(this)
-                                .commitAllowingStateLoss();
-        }
-    }
-
     @Override
     public void onActivityCreated(Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);

mobile/android/base/home/TopSitesPanel.java

@@ -35,7 +35,6 @@ import org.mozilla.gecko.util.ThreadUtils;
 import android.app.Activity;
 import android.content.ContentResolver;
 import android.content.Context;
-import android.content.res.Configuration;
 import android.database.Cursor;
 import android.graphics.Bitmap;
 import android.graphics.Color;
@@ -213,19 +212,6 @@ public class TopSitesPanel extends HomeFragment {
         mGridAdapter = null;
     }
 
-    @Override
-    public void onConfigurationChanged(Configuration newConfig) {
-        super.onConfigurationChanged(newConfig);
-
-        // Detach and reattach the fragment as the layout changes.
-        if (isVisible()) {
-            getFragmentManager().beginTransaction()
-                                .detach(this)
-                                .attach(this)
-                                .commitAllowingStateLoss();
-        }
-    }
-
     @Override
     public void onActivityCreated(Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);