Remove hard-coded colors in Wallpaper Picker

The CLs in this topic remove the hard-coded colors from the app, replacing them with ?android:attr/, ?attr/, and sometimes @color/ that is defined using device default colors.

Fixes: 173549815
Test: none added
Change-Id: I9fa38334b36d971fe74775cfededcdf567112308
diff --git a/res/layout/grid_item_my_photos.xml b/res/layout/grid_item_my_photos.xml
index dbedfbe..ca22fa8 100755
--- a/res/layout/grid_item_my_photos.xml
+++ b/res/layout/grid_item_my_photos.xml
@@ -22,7 +22,7 @@
         android:id="@+id/tile"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        android:background="@color/light_grey"
+        android:background="?android:colorSecondary"
         android:clickable="true"
         android:focusable="true"
         android:foreground="?attr/selectableItemBackground">
@@ -43,14 +43,14 @@
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:layout_alignParentBottom="true"
-            android:background="@color/translucent_black_90_alpha"
+            android:background="?android:colorForeground"
             android:padding="@dimen/rotation_tile_desktop_label_padding">
 
             <TextView
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:text="@string/my_photos_category_title"
-                android:textColor="@color/material_white_100"
+                android:textColor="?android:attr/textColorPrimary"
                 android:textSize="@dimen/rotation_tile_desktop_label_text_size" />
 
         </FrameLayout>