Fixing up styling of Prominent buttons and "view_user" to work better on different bg colors

app/src/main/res/color/prominent_button_color.xml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <selector xmlns:android="http://schemas.android.com/apk/res/android">
-    <item android:state_enabled="false" android:color="@color/gray50"/>
+    <item android:state_enabled="false" android:color="?android:textColorTertiary"/>
     <item android:color="?prominentButtonColor"/>
 </selector>

app/src/main/res/drawable/conversation_view_background.xml

@@ -1,9 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<ripple
-    xmlns:android="http://schemas.android.com/apk/res/android"
-    android:color="?android:colorControlHighlight">
-
-    <item>
-        <color android:color="?colorPrimary" />
-    </item>
-</ripple>

app/src/main/res/drawable/prominent_outline_button_medium_background.xml

@@ -1,13 +1,27 @@
 <?xml version="1.0" encoding="utf-8"?>
-<ripple xmlns:android="http://schemas.android.com/apk/res/android"
-    android:color="?prominentButtonColor">
-    <item>
+<selector xmlns:android="http://schemas.android.com/apk/res/android">
+    <item android:state_enabled="false">
         <shape android:shape="rectangle">
-            <solid android:color="?colorPrimary"/>
+            <solid android:color="@android:color/transparent"/>
             <corners android:radius="@dimen/medium_button_corner_radius" />
             <stroke
-                android:color="?prominentButtonColor"
+                android:color="?android:textColorTertiary"
                 android:width="@dimen/border_thickness" />
         </shape>
     </item>
-</ripple>
+    <item>
+        <ripple
+            android:color="?prominentButtonColor">
+            <item>
+                <shape android:shape="rectangle">
+                    <solid android:color="@android:color/transparent"/>
+                    <corners android:radius="@dimen/medium_button_corner_radius" />
+                    <stroke
+                        android:color="?prominentButtonColor"
+                        android:width="@dimen/border_thickness" />
+                </shape>
+            </item>
+        </ripple>
+    </item>
+</selector>
+

app/src/main/res/layout/view_user.xml

@@ -3,7 +3,7 @@
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="64dp"
-    android:background="@drawable/conversation_view_background"
+    android:background="?attr/selectableItemBackground"
     android:contentDescription="@string/AccessibilityId_contact"
     android:orientation="vertical">