Use Theme.DeviceDefault theme

For API 21 (and later), Theme.DeviceDefault.Light is specified.

This CL must be checked in together with Ic91f28df81.

Bug: 11866784
Bug: 13888366
Bug: 15781377
Change-Id: I01b288473128fc2491d3663e90cab56d0ba2d704
diff --git a/java/res/values-v20/platform-theme.xml b/java/res/values-v21/platform-theme.xml
similarity index 83%
rename from java/res/values-v20/platform-theme.xml
rename to java/res/values-v21/platform-theme.xml
index 52e7f35..2a54798 100644
--- a/java/res/values-v20/platform-theme.xml
+++ b/java/res/values-v21/platform-theme.xml
@@ -18,9 +18,8 @@
 */
 -->
 
-<!-- TODO: This file is temporarily placed under values-v20. -->
-<!-- TODO: It might be moved under values-v21. -->
 <resources xmlns:android="http://schemas.android.com/apk/res/android">
-    <style name="platformActivityTheme" parent="@android:style/Theme.Material.Light" />
-    <style name="platformDialogTheme" parent="@android:style/Theme.Material.Light.Dialog" />
+    <style name="platformActivityTheme" parent="@android:style/Theme.DeviceDefault.Light" />
+    <style name="platformSettingsTheme" parent="@android:style/Theme.DeviceDefault.Light" />
+    <style name="platformDialogTheme" parent="@android:style/Theme.DeviceDefault.Light.Dialog" />
 </resources>
diff --git a/java/res/values/platform-theme.xml b/java/res/values/platform-theme.xml
index 8e131a2..2854ff7 100644
--- a/java/res/values/platform-theme.xml
+++ b/java/res/values/platform-theme.xml
@@ -19,6 +19,7 @@
 -->
 
 <resources xmlns:android="http://schemas.android.com/apk/res/android">
-    <style name="platformActivityTheme" parent="@android:style/Theme.Holo" />
-    <style name="platformDialogTheme" parent="@android:style/Theme.Holo.Dialog" />
+    <style name="platformActivityTheme" parent="@android:style/Theme.DeviceDefault" />
+    <style name="platformSettingsTheme" parent="@android:style/Theme.DeviceDefault" />
+    <style name="platformDialogTheme" parent="@android:style/Theme.DeviceDefault.Dialog" />
 </resources>