Add preliminary graphics of sliding key input preview

Bug: 7548583
Change-Id: Idde6a62f9e64458055c99c893b71c02d1adc7b04
diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index 850b1b8..51a0758 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -83,6 +83,8 @@
         <attr name="touchNoiseThresholdDistance" format="dimension" />
         <!-- Sliding key input enable -->
         <attr name="slidingKeyInputEnable" format="boolean" />
+        <attr name="slidingKeyInputPreviewColor" format="color" />
+        <attr name="slidingKeyInputPreviewWidth" format="dimension" />
         <!-- Key repeat start timeout -->
         <attr name="keyRepeatStartTimeout" format="integer" />
         <!-- Key repeat interval in millisecond. -->