Move virtual_ab makefiles to its own dir.

Also add a readme file.

Test: none

Change-Id: Ia1e02d8fb0c6df13271f208b3ca1dc1f250b085b
diff --git a/target/product/virtual_ab_ota/README.md b/target/product/virtual_ab_ota/README.md
new file mode 100644
index 0000000..c1d0d7d
--- /dev/null
+++ b/target/product/virtual_ab_ota/README.md
@@ -0,0 +1,14 @@
+# Virtual A/B makefiles
+
+Devices that uses Virtual A/B must inherit from one of the makefiles in this directory.
+
+## Structure
+
+```
+launch.mk
+  |- retrofit.mk
+  |- plus_non_ab.mk
+  |- compression.mk
+
+compression_retrofit.mk
+```
diff --git a/target/product/virtual_ab_ota_compression.mk b/target/product/virtual_ab_ota/compression.mk
similarity index 97%
rename from target/product/virtual_ab_ota_compression.mk
rename to target/product/virtual_ab_ota/compression.mk
index 4bab55e..2251187 100644
--- a/target/product/virtual_ab_ota_compression.mk
+++ b/target/product/virtual_ab_ota/compression.mk
@@ -14,7 +14,7 @@
 # limitations under the License.
 #
 
-$(call inherit-product, $(SRC_TARGET_DIR)/product/virtual_ab_ota.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/virtual_ab_ota/launch.mk)
 
 PRODUCT_VENDOR_PROPERTIES += ro.virtual_ab.compression.enabled=true
 
diff --git a/target/product/virtual_ab_ota_compression_retrofit.mk b/target/product/virtual_ab_ota/compression_retrofit.mk
similarity index 100%
rename from target/product/virtual_ab_ota_compression_retrofit.mk
rename to target/product/virtual_ab_ota/compression_retrofit.mk
diff --git a/target/product/virtual_ab_ota.mk b/target/product/virtual_ab_ota/launch.mk
similarity index 100%
rename from target/product/virtual_ab_ota.mk
rename to target/product/virtual_ab_ota/launch.mk
diff --git a/target/product/virtual_ab_ota_plus_non_ab.mk b/target/product/virtual_ab_ota/plus_non_ab.mk
similarity index 97%
rename from target/product/virtual_ab_ota_plus_non_ab.mk
rename to target/product/virtual_ab_ota/plus_non_ab.mk
index 99a10ed..820fa1e 100644
--- a/target/product/virtual_ab_ota_plus_non_ab.mk
+++ b/target/product/virtual_ab_ota/plus_non_ab.mk
@@ -14,7 +14,7 @@
 # limitations under the License.
 #
 
-$(call inherit-product, $(SRC_TARGET_DIR)/product/virtual_ab_ota.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/virtual_ab_ota/launch.mk)
 
 PRODUCT_OTA_FORCE_NON_AB_PACKAGE := true
 
diff --git a/target/product/virtual_ab_ota_retrofit.mk b/target/product/virtual_ab_ota/retrofit.mk
similarity index 97%
rename from target/product/virtual_ab_ota_retrofit.mk
rename to target/product/virtual_ab_ota/retrofit.mk
index 3416a4f..93b42b7 100644
--- a/target/product/virtual_ab_ota_retrofit.mk
+++ b/target/product/virtual_ab_ota/retrofit.mk
@@ -14,7 +14,7 @@
 # limitations under the License.
 #
 
-$(call inherit-product, $(SRC_TARGET_DIR)/product/virtual_ab_ota.mk)
+$(call inherit-product, $(SRC_TARGET_DIR)/product/virtual_ab_ota/launch.mk)
 
 PRODUCT_VIRTUAL_AB_OTA_RETROFIT := true