Service Gesture Detection: don't lock when executing double tap in the framework.

Only lock when obtaining the input filter to avoid deadlock when bringing up talkback settings.
Fix:223673816
Test: Manual. Bring up talkback settings and insure that there is no ten second wait.

Change-Id: Ic26a3a08a7c67b096a7995332e3ed5096fde4847

services/accessibility/java/com/android/server/accessibility/AccessibilityManagerService.java

@@ -4290,11 +4290,15 @@ public class AccessibilityManagerService extends IAccessibilityManager.Stub
     }
 
     private void onDoubleTapInternal(int displayId) {
+        AccessibilityInputFilter inputFilter = null;
         synchronized (mLock) {
             if (mHasInputFilter && mInputFilter != null) {
-                mInputFilter.onDoubleTap(displayId);
+                inputFilter = mInputFilter;
             }
         }
+        if (inputFilter != null) {
+            inputFilter.onDoubleTap(displayId);
+        }
     }
 
     @Override