Import new expand icons

Also update X close icons to be vector drawables, tinting
them to the proper colors where they are currently used.

Test:
Manually verified the following with Bullhead on M (MDA70B):
1. Dropdown icons in compact and full editors are 54% transparent
black.
2. X's next to edit text views are 38% transparent black.
3. X's in search and selection bar are still 54% transparent
black.

Bug: 30160325
Change-Id: Ice24a70f02141f641c389060c37bdc87b727b230
diff --git a/res/values/colors.xml b/res/values/colors.xml
index 771ba44..607b7a0 100644
--- a/res/values/colors.xml
+++ b/res/values/colors.xml
@@ -14,6 +14,11 @@
      limitations under the License.
 -->
 <resources>
+    <!-- 54% black -->
+    <color name="quantum_black_secondary_text">#89000000</color>
+
+    <!-- 38% black -->
+    <color name="quantum_black_hint_text">#61000000</color>
 
     <color name="quickcontact_name_detail_background">#66000000</color>
     <color name="quickcontact_entry_sub_header_text_color">#737373</color>