assist: Fix reported colors/styles for TextView/Switch

Changes to the data provided to AssistStructure:
* Text foreground color is correct even if the view has not yet been
painted.
* Text background color is now always 1 (TEXT_COLOR_UNDEFINED) for a
TextView, as it has no separate concept of background color.
* Switch now reports the text size/color/style of the label text
(usually user visible) rather than the on/off text on the button
itself (usually hidden in Material, and not usually revelant when
visible).

Bug: 21080375
Change-Id: I7e15f68d89510a76cab76031c2c8ca6ca3f32435
diff --git a/core/java/android/widget/Switch.java b/core/java/android/widget/Switch.java
index f42959f..49226cd0 100644
--- a/core/java/android/widget/Switch.java
+++ b/core/java/android/widget/Switch.java
@@ -1374,7 +1374,9 @@
                 newText.append(oldText).append(' ').append(switchText);
                 structure.setText(newText);
             }
-            structure.setTextPaint(mTextPaint);
+            // The style of the label text is provided via the base TextView class. This is more
+            // relevant than the style of the (optional) on/off text on the switch button itself,
+            // so ignore the size/color/style stored this.mTextPaint.
         }
     }