Intent.getAction() can return null

Make sure we don't rely on action being non-null when it could be. This
fixes some paths into this Settings screen.

Bug: 5246883
Change-Id: I13e247ff95f389a45f5031a559d5ca4914082af3
diff --git a/src/com/android/settings/applications/ManageApplications.java b/src/com/android/settings/applications/ManageApplications.java
index c2e68dd..d4abfa8 100644
--- a/src/com/android/settings/applications/ManageApplications.java
+++ b/src/com/android/settings/applications/ManageApplications.java
@@ -563,11 +563,11 @@
         if (className.equals(RunningServicesActivity.class.getName())) {
             defaultTabTag = TAB_RUNNING;
         } else if (className.equals(StorageUseActivity.class.getName())
-                || action.equals(Intent.ACTION_MANAGE_PACKAGE_STORAGE)) {
+                || Intent.ACTION_MANAGE_PACKAGE_STORAGE.equals(action)) {
             mSortOrder = SORT_ORDER_SIZE;
             mFilterApps = FILTER_APPS_ALL;
             defaultTabTag = TAB_ALL;
-        } else if (action.equals(Settings.ACTION_MANAGE_ALL_APPLICATIONS_SETTINGS)) {
+        } else if (Settings.ACTION_MANAGE_ALL_APPLICATIONS_SETTINGS.equals(action)) {
             // Select the all-apps tab, with the default sorting
             defaultTabTag = TAB_ALL;
         }