Implement LOCAL_COMPRESSED_MODULE.

- Prebuilts with LOCAL_MODULE_CLASS == APPS and BUILD_PACKAGE that
  define LOCAL_COMPRESSED_MODULE := true will be installed compressed
  in the system partition.
- The compression algorithm is simple gzip for now.

In addition :
- Compressed modules are not dex-preopted.
- JNI shared libraries are always embedded inside compressed modules,
  they are never installed as separate files on the FS.

Test: Manual
Bug: 63802184

Change-Id: Id12b1ff0b1d68791ec1178783f7e78910e122a33
diff --git a/core/package_internal.mk b/core/package_internal.mk
index 74dd15e..28c3a08 100644
--- a/core/package_internal.mk
+++ b/core/package_internal.mk
@@ -215,8 +215,19 @@
 LOCAL_INTERMEDIATE_TARGETS += $(R_file_stamp)
 endif
 
+ifdef LOCAL_COMPRESSED_MODULE
+ifneq (true,$(LOCAL_COMPRESSED_MODULE))
+$(call pretty-error, Unknown value for LOCAL_COMPRESSED_MODULE $(LOCAL_COMPRESSED_MODULE))
+endif
+endif
+
+ifdef LOCAL_COMPRESSED_MODULE
+LOCAL_BUILT_MODULE_STEM := package.apk.gz
+LOCAL_INSTALLED_MODULE_STEM := $(LOCAL_MODULE).apk.gz
+else  # !LOCAL_COMPRESSED_MODULE
 LOCAL_BUILT_MODULE_STEM := package.apk
 LOCAL_INSTALLED_MODULE_STEM := $(LOCAL_MODULE).apk
+endif
 
 LOCAL_PROGUARD_ENABLED:=$(strip $(LOCAL_PROGUARD_ENABLED))
 ifndef LOCAL_PROGUARD_ENABLED
@@ -307,6 +318,12 @@
 LOCAL_AAPT_FLAGS += --auto-add-overlay --extra-packages com.android.databinding.library
 endif  # LOCAL_DATA_BINDING
 
+# If the module is a compressed module, we don't pre-opt it because its final
+# installation location will be the data partition.
+ifdef LOCAL_COMPRESSED_MODULE
+LOCAL_DEX_PREOPT := false
+endif
+
 include $(BUILD_SYSTEM)/android_manifest.mk
 
 #################################
@@ -358,6 +375,10 @@
 my_apk_split_configs :=
 
 ifdef LOCAL_PACKAGE_SPLITS
+ifdef LOCAL_COMPRESSED_MODULE
+$(error $(LOCAL_MODULE): LOCAL_COMPRESSED_MODULE is not currently supported for split installs)
+endif  # LOCAL_COMPRESSED_MODULE
+
 my_apk_split_configs := $(LOCAL_PACKAGE_SPLITS)
 my_split_suffixes := $(subst $(comma),_,$(my_apk_split_configs))
 built_apk_splits := $(foreach s,$(my_split_suffixes),$(intermediates)/package_$(s).apk)
@@ -571,6 +592,9 @@
 else
 $(LOCAL_BUILT_MODULE) : $(all_res_assets) $(full_android_manifest) $(AAPT)
 endif
+ifdef LOCAL_COMPRESSED_MODULE
+$(LOCAL_BUILT_MODULE) : $(MINIGZIP)
+endif
 	@echo "target Package: $(PRIVATE_MODULE) ($@)"
 ifdef LOCAL_USE_AAPT2
 	$(call copy-file-to-new-target)
@@ -606,6 +630,9 @@
 endif
 endif
 	$(sign-package)
+ifdef LOCAL_COMPRESSED_MODULE
+	$(compress-package)
+endif  # LOCAL_COMPRESSED_MODULE
 
 ###############################
 ## Build dpi-specific apks, if it's apps_only build.