Merge "Ignore events when there is no focused stack." into pi-dev

        try {

            final ActivityManager.StackInfo focusedStack = mInjector.getFocusedStack();

            if (focusedStack != null && focusedStack.topActivity != null) {

                builder.setUserId(focusedStack.userId);

                builder.setPackageName(focusedStack.topActivity.getPackageName());

            } else {

                // Ignore the event because we can't determine user / package.

                if (DEBUG) {

                    Slog.d(TAG, "Ignoring event due to null focusedStack.");

                }

                return;

            }

        } catch (RemoteException e) {

            // Really shouldn't be possible.

            return;