Use @android:style/Theme.Black.NoTitleBar to avoid white flash

Using this theme appears to remove the white flash during startup.

R=eseidel@chromium.org, jackson@google.com

Review URL: https://codereview.chromium.org/1240433004 .

sdk/example/demo_launcher/apk/AndroidManifest.xml

@@ -10,11 +10,11 @@
     <uses-feature android:name="android.hardware.sensor.accelerometer" android:required="true" />
 
     <application android:icon="@mipmap/ic_launcher" android:label="Sky" android:name="SkyDemoApplication">
-        <activity android:configChanges="orientation|keyboardHidden|keyboard|screenSize" android:documentLaunchMode="always" android:hardwareAccelerated="true" android:launchMode="standard" android:name="SkyDemoActivity" android:theme="@android:style/Theme.Holo.Light.NoActionBar">
+        <activity android:configChanges="orientation|keyboardHidden|keyboard|screenSize" android:documentLaunchMode="always" android:hardwareAccelerated="true" android:launchMode="standard" android:name="SkyDemoActivity" android:theme="@android:style/Theme.Black.NoTitleBar">
             <intent-filter>
                 <action android:name="android.intent.action.MAIN" />
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
     </application>
- </manifest>
\ No newline at end of file
+ </manifest>

sdk/example/fitness/apk/AndroidManifest.xml

@@ -12,7 +12,7 @@
     <application android:name="org.domokit.sky.shell.SkyApplication" android:label="Fitness">
         <activity android:name="org.domokit.sky.shell.SkyActivity"
                   android:launchMode="singleTask"
-                  android:theme="@android:style/Theme.Holo.Light.NoActionBar"
+                  android:theme="@android:style/Theme.Black.NoTitleBar"
                   android:configChanges="orientation|keyboardHidden|keyboard|screenSize"
                   android:hardwareAccelerated="true">
             <intent-filter>

sdk/example/mine_digger/apk/AndroidManifest.xml

@@ -12,7 +12,7 @@
     <application android:name="org.domokit.sky.shell.SkyApplication" android:label="Mine Digger">
         <activity android:name="org.domokit.sky.shell.SkyActivity"
                   android:launchMode="singleTask"
-                  android:theme="@android:style/Theme.Holo.Light.NoActionBar"
+                  android:theme="@android:style/Theme.Black.NoTitleBar"
                   android:configChanges="orientation|keyboardHidden|keyboard|screenSize"
                   android:hardwareAccelerated="true">
             <intent-filter>

sdk/example/stocks/apk/AndroidManifest.xml

@@ -12,7 +12,7 @@
     <application android:name="org.domokit.sky.shell.SkyApplication" android:label="Stocks">
         <activity android:name="org.domokit.sky.shell.SkyActivity"
                   android:launchMode="singleTask"
-                  android:theme="@android:style/Theme.Holo.Light.NoActionBar"
+                  android:theme="@android:style/Theme.Black.NoTitleBar"
                   android:configChanges="orientation|keyboardHidden|keyboard|screenSize"
                   android:hardwareAccelerated="true">
             <intent-filter>