Clean up of system UI flag demo, doc markup for overscan demo.

Change-Id: Iaef99a4c1aeebbd327bcbc42b27d20c8065f8d27

samples/ApiDemos/AndroidManifest.xml

@@ -2298,7 +2298,7 @@
             </intent-filter>
         </activity>
 
-        <activity android:name=".view.OverscanActivity"
+        <activity android:name=".view.SystemUIModes"
                 android:label="Views/System UI Visibility/System UI Modes"
                 android:uiOptions="splitActionBarWhenNarrow">
             <intent-filter>

samples/ApiDemos/res/layout/overscan_activity.xml

@@ -14,11 +14,18 @@
      limitations under the License.
 -->
 
+<!-- BEGIN_INCLUDE(complete) -->
+<!-- This layout is designed for use with FLAG_LAYOUT_IN_OVERSCAN, so its window will
+     be placed into the overscan region of the display (if there is one).  Thus the contents
+     of the top-level view may be obscured around the edges by the display, leaving the
+     edge of the box background used here invisible. -->
 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:background="@drawable/box_white">
 
+    <!-- This is still in the same position as the top-level FrameLayout, so the contentx
+        of this TextView may also be obscured. -->
     <TextView
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
@@ -27,10 +34,16 @@
         android:textAppearance="?android:attr/textAppearanceMedium"
         android:text="Overscan" />
 
+    <!-- This FrameLayout uses android:fitsSystemWindows to have its padding adjusted so
+         that within that space its content is offset to not be obscured by the overscan
+         region (or also system decors that are covering its UI. -->
     <FrameLayout
         android:layout_width="match_parent"
         android:layout_height="match_parent"
         android:fitsSystemWindows="true">
+
+        <!-- Now that we are within the padding region of the parent FrameLayout, we can
+             safely place content that will be visible to the user. -->
         <ImageView
             android:layout_width="match_parent"
             android:layout_height="match_parent"
@@ -47,6 +60,8 @@
             android:layout_marginLeft="3dp"
             android:textAppearance="?android:attr/textAppearanceMedium"
             android:text="Content" />
+
     </FrameLayout>
 
 </FrameLayout>
+<!-- END_INCLUDE(complete) -->

samples/ApiDemos/res/layout/system_ui_modes.xml

@@ -17,7 +17,7 @@
 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent" android:layout_height="match_parent"
     >
-    <view class="com.example.android.apis.view.OverscanActivity$IV"
+    <view class="com.example.android.apis.view.SystemUIModes$IV"
         android:id="@+id/image"
         android:src="@drawable/frantic"
         android:layout_width="match_parent"

samples/ApiDemos/src/com/example/android/apis/view/SystemUIModes.java

@@ -27,12 +27,10 @@ import android.os.Bundle;
 import android.util.AttributeSet;
 import android.util.DisplayMetrics;
 import android.view.ActionMode;
-import android.view.KeyEvent;
 import android.view.Menu;
 import android.view.MenuInflater;
 import android.view.MenuItem;
 import android.view.View;
-import android.view.View.OnClickListener;
 import android.view.Window;
 import android.view.WindowManager;
 import android.widget.CheckBox;
@@ -51,10 +49,10 @@ import com.example.android.apis.R;
  * the system decor, in order to better focus the user's attention or use available screen real
  * estate on the task at hand.
  */
-public class OverscanActivity extends Activity
+public class SystemUIModes extends Activity
         implements OnQueryTextListener, ActionBar.TabListener {
     public static class IV extends ImageView implements View.OnSystemUiVisibilityChangeListener {
-        private OverscanActivity mActivity;
+        private SystemUIModes mActivity;
         private ActionMode mActionMode;
         public IV(Context context) {
             super(context);
@@ -62,7 +60,7 @@ public class OverscanActivity extends Activity
         public IV(Context context, AttributeSet attrs) {
             super(context, attrs);
         }
-        public void setActivity(OverscanActivity act) {
+        public void setActivity(SystemUIModes act) {
             setOnSystemUiVisibilityChangeListener(this);
             mActivity = act;
         }
@@ -161,7 +159,7 @@ public class OverscanActivity extends Activity
     };
     TextView mMetricsText;
 
-    public OverscanActivity() {
+    public SystemUIModes() {
     }
 
     @Override
@@ -170,7 +168,7 @@ public class OverscanActivity extends Activity
 
         getWindow().requestFeature(Window.FEATURE_ACTION_BAR_OVERLAY);
 
-        setContentView(R.layout.overscan);
+        setContentView(R.layout.system_ui_modes);
         mImage = (IV) findViewById(R.id.image);
         mImage.setActivity(this);