WidgetTray UI tweak

- set fixed image view width
- fade in when widget bitmap populates
- widget dimension is next to the widget name text.
- elevation of the widgets content and the reveal view is the same

b/19897708

Change-Id: Ia656144412e7d63a491ce67ff15fb58c05d9a9d9
diff --git a/res/values/dimens.xml b/res/values/dimens.xml
index 101b755..cad60fb 100644
--- a/res/values/dimens.xml
+++ b/res/values/dimens.xml
@@ -81,15 +81,16 @@
 <!-- Widget tray -->
     <dimen name="widget_container_inset">8dp</dimen>
     <dimen name="widget_preview_size">140dp</dimen>
-    <dimen name="widget_preview_padding_left">16dp</dimen>
-    <dimen name="widget_preview_padding_right">16dp</dimen>
     <dimen name="widget_preview_padding_top">8dp</dimen>
     <dimen name="widget_preview_label_vertical_padding">8dp</dimen>
     <dimen name="widget_preview_label_horizontal_padding">8dp</dimen>
+    <dimen name="widget_preview_horizontal_padding">8dp</dimen>
 
     <dimen name="widget_section_height">52dp</dimen>
     <dimen name="widget_section_icon_padding">8dp</dimen>
 
+    <!-- Equation: widget_preview_size + 2 * widget_preview_padding_horizontal -->
+    <dimen name="widget_preview_container_width">156dp</dimen>
     <dimen name="widget_cell_height">160dp</dimen>
 
     <!-- Padding applied to shortcut previews -->