Make activity dialog sample look more like an alert dialog.

Change-Id: I808604968a647eaedc703a76afa7231812723399
diff --git a/samples/ApiDemos/res/layout/dialog_activity.xml b/samples/ApiDemos/res/layout/dialog_activity.xml
index b3a5689..42a7753 100644
--- a/samples/ApiDemos/res/layout/dialog_activity.xml
+++ b/samples/ApiDemos/res/layout/dialog_activity.xml
@@ -20,25 +20,34 @@
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
         android:layout_width="match_parent" android:layout_height="match_parent"
         android:orientation="vertical"
-        android:padding="4dip" android:gravity="center_horizontal">
+        android:padding="4dp" android:gravity="center_horizontal">
+    
+    <!-- Message to show to use. -->
     <TextView android:id="@+id/text"
         android:layout_width="wrap_content" android:layout_height="wrap_content"
         android:gravity="center_vertical|center_horizontal"
+        android:textStyle="?android:attr/textAppearanceMedium"
         android:text="@string/dialog_activity_text"/>
-    <LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content"
-            android:orientation="horizontal" android:paddingTop="4dip">
-        <Button android:id="@+id/add"
-            android:layout_width="wrap_content" android:layout_height="wrap_content"
-            android:text="@string/dialog_activity_add">
-            <requestFocus />
-        </Button>
-        <Button android:id="@+id/remove"
-            android:layout_width="wrap_content" android:layout_height="wrap_content"
-            android:text="@string/dialog_activity_remove">
-        </Button>
-    </LinearLayout>
+        
+    <!-- Container in which we are going to add and remove views, to demonstrate
+         how the layout adjusts based on size. -->
     <LinearLayout android:id="@+id/inner_content"
             android:layout_width="wrap_content" android:layout_height="wrap_content"
-            android:orientation="horizontal" android:paddingTop="4dip">
+            android:orientation="horizontal"
+            android:paddingTop="4dp" android:paddingBottom="4dp">
+    </LinearLayout>
+    
+    <!-- Alert dialog style buttons along the bottom. -->
+    <LinearLayout style="?android:attr/alertDialogButtonGroupStyle"
+        android:layout_width="match_parent" android:layout_height="wrap_content"
+        android:measureWithLargestChild="true">
+        <Button style="?android:attr/borderlessButtonStyle" android:id="@+id/add"
+            android:layout_width="wrap_content" android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="@string/dialog_activity_add" />
+        <Button style="?android:attr/borderlessButtonStyle" android:id="@+id/remove"
+            android:layout_width="wrap_content" android:layout_height="wrap_content"
+            android:layout_weight="1"
+            android:text="@string/dialog_activity_remove" />
     </LinearLayout>
 </LinearLayout>