talkback: add null check to ComponentName

- Reintroduce null check from ag/25620669

Test: build
Fix: 323297932
Change-Id: Idef0b0afd593fae4d2604e7f561ef41a51d7f517
diff --git a/services/core/java/com/android/server/policy/TalkbackShortcutController.java b/services/core/java/com/android/server/policy/TalkbackShortcutController.java
index 906da2f..b05a421 100644
--- a/services/core/java/com/android/server/policy/TalkbackShortcutController.java
+++ b/services/core/java/com/android/server/policy/TalkbackShortcutController.java
@@ -59,6 +59,10 @@
         final Set<ComponentName> enabledServices =
                 AccessibilityUtils.getEnabledServicesFromSettings(mContext, userId);
         ComponentName componentName = getTalkbackComponent();
+        if (componentName == null) {
+            return false;
+        }
+
         boolean isTalkbackAlreadyEnabled = enabledServices.contains(componentName);
 
         if (isTalkBackShortcutGestureEnabled()) {
@@ -67,7 +71,7 @@
                     isTalkbackAlreadyEnabled);
 
             // log stem triple press telemetry if it's a talkback enabled event.
-            if (componentName != null && isTalkbackAlreadyEnabled) {
+            if (isTalkbackAlreadyEnabled) {
                 logStemTriplePressAccessibilityTelemetry(componentName);
             }
         }