Special handling of one key mini-keyboard to mitigate visual flicker

Use pre-computed width and height of mini keyboard if
 * Popup key preview is enabled
 * The mini keyboard has only one key
 * Pre-computed width and height are specified

Bug: 5248783
Change-Id: I53475698e87d5bd67d36e63323c25a9e9f18fbb1
diff --git a/java/res/values/attrs.xml b/java/res/values/attrs.xml
index 4dfa5ab..e569e83 100644
--- a/java/res/values/attrs.xml
+++ b/java/res/values/attrs.xml
@@ -88,6 +88,10 @@
         <attr name="keyPreviewLeftBackground" format="reference" />
         <!-- The background for the right edge key press feedback. -->
         <attr name="keyPreviewRightBackground" format="reference" />
+        <!-- The width of rectangle part of the key press feedback background. -->
+        <attr name="keyPreviewBackgroundWidth" format="dimension" />
+        <!-- The height of rectangle part of the key press feedback background. -->
+        <attr name="keyPreviewBackgroundHeight" format="dimension" />
         <!-- The text color for key press feedback. -->
         <attr name="keyPreviewTextColor" format="color" />
         <!-- Vertical offset of the key press feedback from the key. -->