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/layout/search_bar_expanded.xml b/res/layout/search_bar_expanded.xml
index ecadbd1..945521f 100644
--- a/res/layout/search_bar_expanded.xml
+++ b/res/layout/search_bar_expanded.xml
@@ -53,10 +53,10 @@
         android:layout_height="@dimen/search_box_close_icon_size"
         android:layout_width="@dimen/search_box_close_icon_size"
         android:padding="@dimen/search_box_close_icon_padding"
-        android:src="@drawable/ic_close_black_24dp"
+        android:src="@drawable/ic_close_24dp"
+        android:tint="@color/quantum_black_secondary_text"
         android:clickable="true"
         android:background="?attr/selectableItemBackgroundBorderless"
-        android:contentDescription="@string/description_clear_search"
-        android:alpha="@dimen/close_icon_alpha" />
+        android:contentDescription="@string/description_clear_search" />
 
 </LinearLayout>