Merge "Document apex and apex_test" am: a871ee2067 am: e0d6f7d9d3 am: d27a333182

Change-Id: Iabbff9fe6d65618de71347ead245fc43136454c9

apex/apex.go

@@ -2376,12 +2376,16 @@ func ApexBundleFactory(testApex bool, artApex bool) android.Module {
 	return bundle
 }
 
+// apex_test is an APEX for testing. The difference from the ordinary apex module type is that
+// certain compatibility checks such as apex_available are not done for apex_test.
 func testApexBundleFactory() android.Module {
 	bundle := newApexBundle()
 	bundle.testApex = true
 	return bundle
 }
 
+// apex packages other modules into an APEX file which is a packaging format for system-level
+// components like binaries, shared libraries, etc.
 func BundleFactory() android.Module {
 	return newApexBundle()
 }