Fixed crashes in Android 2.x due to accesibility code

src/com/owncloud/android/ui/activity/FileDisplayActivity.java

@@ -1393,9 +1393,9 @@ OnSslUntrustedCertListener, OnEnforceableRefreshListener {
             actionBar.setDisplayShowTitleEnabled(!noRoot); 
             if (!noRoot) {
                 actionBar.setTitle(getString(R.string.default_display_name_for_root_folder));
-                View actionBarView = getWindow().getDecorView().findViewById(actionBarTitleId);
-                if (actionBarView != null) {    // it's null in Android 2.x (at least)
-                    actionBarView.setContentDescription(getString(R.string.default_display_name_for_root_folder));
+                View actionBarTitleView = getWindow().getDecorView().findViewById(actionBarTitleId);
+                if (actionBarTitleView != null) {    // it's null in Android 2.x
+                    actionBarTitleView.setContentDescription(getString(R.string.default_display_name_for_root_folder));
                 }
             }
             actionBar.setNavigationMode(!noRoot ? ActionBar.NAVIGATION_MODE_STANDARD : ActionBar.NAVIGATION_MODE_LIST);
@@ -1406,7 +1406,11 @@ OnSslUntrustedCertListener, OnEnforceableRefreshListener {
             actionBar.setDisplayShowTitleEnabled(true);
             actionBar.setTitle(chosenFile.getFileName());
             actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
-            getWindow().getDecorView().findViewById(actionBarTitleId).setContentDescription(chosenFile.getFileName());
+            View actionBarTitleView = getWindow().getDecorView().findViewById(actionBarTitleId);
+            if (actionBarTitleView != null) {    // it's null in Android 2.x
+                getWindow().getDecorView().findViewById(actionBarTitleId).
+                        setContentDescription(chosenFile.getFileName());
+            }
         }
     }
 

src/com/owncloud/android/ui/activity/Preferences.java

@@ -119,7 +119,11 @@ public class Preferences extends SherlockPreferenceActivity
 
         // For adding content description tag to a title field in the action bar
         int actionBarTitleId = getResources().getIdentifier("action_bar_title", "id", "android");
-        getWindow().getDecorView().findViewById(actionBarTitleId).setContentDescription(getString(R.string.actionbar_settings));
+        View actionBarTitleView = getWindow().getDecorView().findViewById(actionBarTitleId);
+        if (actionBarTitleView != null) {    // it's null in Android 2.x
+            getWindow().getDecorView().findViewById(actionBarTitleId).
+                    setContentDescription(getString(R.string.actionbar_settings));
+        }
 
         // Load the accounts category for adding the list of accounts
         mAccountsPrefCategory = (PreferenceCategory) findPreference("accounts_category");