[Android] Fix the issue that date picker is not work

In the patch crosswalk-project#3857(decouple XWalkView from the activity), we need
use WindowAndroid instead of ActivityWindowAndroid as the top window
of XWalkView, but that will prevent DateTimeChooserAndroid activity
to to launched.

Here we create WindowAndroid or ActivityWindowAndroid according to
the context type.

BUG=XWALK-7269

runtime/android/core_internal/src/org/xwalk/core/internal/XWalkContent.java

@@ -56,6 +56,7 @@
 import org.chromium.content_public.browser.WebContents;
 import org.chromium.content_public.browser.navigation_controller.UserAgentOverrideOption;
 import org.chromium.media.MediaPlayerBridge;
+import org.chromium.ui.base.ActivityWindowAndroid;
 import org.chromium.ui.base.WindowAndroid;
 import org.chromium.ui.gfx.DeviceDisplayInfo;
 import org.json.JSONArray;
@@ -137,8 +138,9 @@ public XWalkContent(Context context, String animatable, XWalkViewInternal xwView
             mContentsClientBridge);
         mIoThreadClient = new XWalkIoThreadClientImpl();
 
-        // Initialize mWindow which is needed by content
-        mWindow = new WindowAndroid(context);
+        // Initialize mWindow which is needed by content.
+        mWindow = WindowAndroid.activityFromContext(context) != null ?
+                new ActivityWindowAndroid(context) : new WindowAndroid(context);
 
         SharedPreferences sharedPreferences = new InMemorySharedPreferences();
         mGeolocationPermissions = new XWalkGeolocationPermissions(sharedPreferences);