[Android] Add content scheme support

The content scheme is for the Uris used by android content
provider. They are commonly used on android to retrieve
resources.

For detail information of android content provider, please referring
http://developer.android.com/guide/topics/providers/content-providers.html.

BUG=https://crosswalk-project.org/jira/browse/XWALK-165
TEST=org.xwalk.core.xwview.test.LoadUrlTest#testContentUrl
Merge pull request #1088 from wang16/content_scheme

[Android] Add content scheme support