perform exit cleanup when browser is closed regardless of whether last tab is deleted or not

app/src/main/java/acr/browser/lightning/activity/BrowserActivity.java

@@ -1068,7 +1068,7 @@ public abstract class BrowserActivity extends ThemableBrowserActivity implements
         Log.d(Constants.TAG, "deleted tab");
     }
 
-    private void performExitCleanUp() {
+    public void performExitCleanUp() {
         final LightningView currentTab = mTabsManager.getCurrentTab();
         if (mPreferences.getClearCacheExit() && currentTab != null && !isIncognito()) {
             WebUtils.clearCache(currentTab.getWebView());

app/src/main/java/acr/browser/lightning/activity/IncognitoActivity.java

@@ -58,6 +58,7 @@ public class IncognitoActivity extends BrowserActivity {
     @Override
     public void closeActivity() {
         closeDrawers();
+        performExitCleanUp();
         finish();
     }
 }

app/src/main/java/acr/browser/lightning/activity/MainActivity.java

@@ -59,6 +59,7 @@ public class MainActivity extends BrowserActivity {
     @Override
     public void closeActivity() {
         closeDrawers();
+        performExitCleanUp();
         moveTaskToBack(true);
     }