Bug 1305439 - Store the last selected tab in GeckoApp in onPause and switch back to it in onResume. r=sebastian

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

@@ -160,6 +160,7 @@ public abstract class GeckoApp
 
     public static final String SAVED_STATE_IN_BACKGROUND   = "inBackground";
     public static final String SAVED_STATE_PRIVATE_SESSION = "privateSession";
+    public static final String SAVED_STATE_LAST_TAB        = "lastTab";
 
     // Delay before running one-time "cleanup" tasks that may be needed
     // after a version upgrade.
@@ -202,6 +203,8 @@ public abstract class GeckoApp
 
     private EventDispatcher eventDispatcher;
 
+    private Tab lastSelectedTab = null;
+
     private static final class LastSessionParser extends SessionParser {
         private JSONArray tabs;
         private JSONObject windowObject;
@@ -583,6 +586,15 @@ public abstract class GeckoApp
 
         outState.putBoolean(SAVED_STATE_IN_BACKGROUND, isApplicationInBackground());
         outState.putString(SAVED_STATE_PRIVATE_SESSION, mPrivateBrowsingSession);
+        outState.putInt(SAVED_STATE_LAST_TAB, lastSelectedTab.getId());
+    }
+
+    @Override
+    protected void onRestoreInstanceState(final Bundle state) {
+        super.onRestoreInstanceState(state);
+
+        final int tabId = state.getInt(SAVED_STATE_LAST_TAB);
+        Tabs.getInstance().selectTab(tabId);
     }
 
     public void addTab() { }
@@ -2080,6 +2092,10 @@ public abstract class GeckoApp
 
         GeckoAppShell.setGeckoInterface(this);
 
+        if (lastSelectedTab != null) {
+            Tabs.getInstance().selectTab(lastSelectedTab.getId());
+        }
+
         int newOrientation = getResources().getConfiguration().orientation;
         if (GeckoScreenOrientation.getInstance().update(newOrientation)) {
             refreshChrome();
@@ -2154,6 +2170,8 @@ public abstract class GeckoApp
             return;
         }
 
+        lastSelectedTab = Tabs.getInstance().getSelectedTab();
+
         final HealthRecorder rec = mHealthRecorder;
         final Context context = this;