Cleanup Bookmarks, History, and SavedPages screen

- Redesigned bookmark thumbnail view
- Custom ImageView to scale the thumbnail properly
- Fix column count in bookmark expandable view
- Disable GroupView if we have only one account in bookmark

Change-Id: I2fccae50b9e96c909744bd5c7d0af7b373136c54
diff --git a/res/values-sw600dp/styles.xml b/res/values-sw600dp/styles.xml
index 44fe540..bcfb749 100644
--- a/res/values-sw600dp/styles.xml
+++ b/res/values-sw600dp/styles.xml
@@ -25,4 +25,7 @@
         <item name="android:actionBarSize">56dip</item>
     </style>
 
+    <style name="ComboViewTheme" parent="@style/BrowserBase">
+    </style>
+
 </resources>