Add conscrypt updatable certificates.

This cl adds a new PrebuiltEtcCaCertsFactory used by ca_certificates_apex in order to create the prebuilts used by the conscrypt apex.

Test: TrustedCertificateStoreTest
Change-Id: Iecac0e4b7ccdce77abb5140db944ea6f42c7d77f
diff --git a/etc/prebuilt_etc.go b/etc/prebuilt_etc.go
index baad58e..b0660df 100644
--- a/etc/prebuilt_etc.go
+++ b/etc/prebuilt_etc.go
@@ -54,6 +54,7 @@
 func RegisterPrebuiltEtcBuildComponents(ctx android.RegistrationContext) {
 	ctx.RegisterModuleType("prebuilt_etc", PrebuiltEtcFactory)
 	ctx.RegisterModuleType("prebuilt_etc_host", PrebuiltEtcHostFactory)
+	ctx.RegisterModuleType("prebuilt_etc_cacerts", PrebuiltEtcCaCertsFactory)
 	ctx.RegisterModuleType("prebuilt_root", PrebuiltRootFactory)
 	ctx.RegisterModuleType("prebuilt_root_host", PrebuiltRootHostFactory)
 	ctx.RegisterModuleType("prebuilt_usr_share", PrebuiltUserShareFactory)
@@ -455,6 +456,17 @@
 	return module
 }
 
+// prebuilt_etc_host is for a host prebuilt artifact that is installed in
+// <partition>/etc/<sub_dir> directory.
+func PrebuiltEtcCaCertsFactory() android.Module {
+	module := &PrebuiltEtc{}
+	InitPrebuiltEtcModule(module, "cacerts")
+	// This module is device-only
+	android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibFirst)
+	android.InitBazelModule(module)
+	return module
+}
+
 // prebuilt_root is for a prebuilt artifact that is installed in
 // <partition>/ directory. Can't have any sub directories.
 func PrebuiltRootFactory() android.Module {