A few little tweaks to system ui flag demos.

Change-Id: Ib4c3b45e8d67200a2b4f3a8b0daee198b24bad0f

samples/ApiDemos/AndroidManifest.xml

@@ -2225,7 +2225,7 @@
 
         <activity android:name=".view.ContentBrowserActivity"
                 android:label="Views/System UI Visibility/Content Browser"
-                android:theme="@android:style/Theme.Holo.Light"
+                android:theme="@android:style/Theme.Holo.Light.DarkActionBar"
                 android:uiOptions="splitActionBarWhenNarrow">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />

samples/ApiDemos/res/layout/content_browser.xml

@@ -34,9 +34,9 @@
             android:layout_height="wrap_content"
             android:layout_gravity="top|center_horizontal"
             android:textColor="#ff000000"
-            android:background="#c0f0f0f0"
+            android:background="#c0ffffff"
             android:textAppearance="?android:attr/textAppearanceLarge"
-            android:gravity="left"
+            android:gravity="center"
             android:padding="16dp"
             android:text="A title goes here"
             />

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

@@ -147,6 +147,7 @@ public class VideoPlayerActivity extends Activity
         void setPlayPaused(boolean paused) {
             mPaused = paused;
             mPlayButton.setText(paused ? R.string.play : R.string.pause);
+            setKeepScreenOn(!paused);
             setNavVisibility(true);
         }
 
@@ -166,7 +167,7 @@ public class VideoPlayerActivity extends Activity
                     h.removeCallbacks(mNavHider);
                     if (!mMenusOpen && !mPaused) {
                         // If the menus are open or play is paused, we will not auto-hide.
-                        h.postDelayed(mNavHider, 3000);
+                        h.postDelayed(mNavHider, 1500);
                     }
                 }
             }