Fix dark theme in search.

Fixed #7821

res/drawable/header_search_background.xml

@@ -7,7 +7,7 @@
     </item>
     <item android:top="1dp">
         <shape android:shape="rectangle" >
-            <solid android:color="@color/white" />
+            <solid android:color="?attr/search_background" />
         </shape>
     </item>
 </layer-list>

res/layout/fragment_search.xml

@@ -9,7 +9,7 @@
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:gravity="center"
-        android:background="@color/white"
+        android:background="?attr/search_background"
         android:visibility="gone" />
 
     <android.support.v7.widget.RecyclerView

res/values/attrs.xml

@@ -135,6 +135,7 @@
     <attr name="shared_contact_details_titlebar" format="color"/>
 
     <attr name="search_toolbar_background" format="color"/>
+    <attr name="search_background" format="color"/>
 
     <attr name="contact_list_divider" format="reference"/>
 

res/values/themes.xml

@@ -240,6 +240,7 @@
         <item name="preferenceTheme">@style/PreferenceThemeOverlay.Fix</item>
 
         <item name="search_toolbar_background">@color/white</item>
+        <item name="search_background">@color/white</item>
         <item name="invite_background">@color/signal_primary</item>
     </style>
 
@@ -364,6 +365,7 @@
         <item name="group_members_dialog_icon">@drawable/ic_group_white_24dp</item>
         <item name="preferenceTheme">@style/PreferenceThemeOverlay.Fix</item>
         <item name="search_toolbar_background">@color/black</item>
+        <item name="search_background">@color/black</item>
         <item name="invite_background">@color/black</item>
     </style>