AAPT2: optionally keep resources without default value

Teach "aapt2 link" about a new flag --no-resource-removal. When given,
aapt2 will not filter out resources that lack default values. This is
useful mostly when building overlay packages that define resources for
non-default configurations, such as only for values-sv.

Test: manual: build package with resource only in values-vs, verify apk with aapt2 dump
Change-Id: Idc513bcb3f43bbff7f073163562c3dfccdb9bc9b
diff --git a/core/tests/overlaytests/device/test-apps/AppOverlayOne/Android.mk b/core/tests/overlaytests/device/test-apps/AppOverlayOne/Android.mk
index edad4b2..97a3d00 100644
--- a/core/tests/overlaytests/device/test-apps/AppOverlayOne/Android.mk
+++ b/core/tests/overlaytests/device/test-apps/AppOverlayOne/Android.mk
@@ -20,4 +20,6 @@
 LOCAL_SDK_VERSION := current
 LOCAL_COMPATIBILITY_SUITE := device-tests
 LOCAL_CERTIFICATE := platform
+LOCAL_USE_AAPT2 := true
+LOCAL_AAPT_FLAGS := --no-resource-removal
 include $(BUILD_PACKAGE)
diff --git a/core/tests/overlaytests/device/test-apps/AppOverlayTwo/Android.mk b/core/tests/overlaytests/device/test-apps/AppOverlayTwo/Android.mk
index 3fae8e1..a347025 100644
--- a/core/tests/overlaytests/device/test-apps/AppOverlayTwo/Android.mk
+++ b/core/tests/overlaytests/device/test-apps/AppOverlayTwo/Android.mk
@@ -20,4 +20,6 @@
 LOCAL_SDK_VERSION := current
 LOCAL_COMPATIBILITY_SUITE := device-tests
 LOCAL_CERTIFICATE := platform
+LOCAL_USE_AAPT2 := true
+LOCAL_AAPT_FLAGS := --no-resource-removal
 include $(BUILD_PACKAGE)
diff --git a/core/tests/overlaytests/device/test-apps/FrameworkOverlay/Android.mk b/core/tests/overlaytests/device/test-apps/FrameworkOverlay/Android.mk
index c352c05..e4819e1 100644
--- a/core/tests/overlaytests/device/test-apps/FrameworkOverlay/Android.mk
+++ b/core/tests/overlaytests/device/test-apps/FrameworkOverlay/Android.mk
@@ -20,4 +20,6 @@
 LOCAL_SDK_VERSION := current
 LOCAL_COMPATIBILITY_SUITE := device-tests
 LOCAL_CERTIFICATE := platform
+LOCAL_USE_AAPT2 := true
+LOCAL_AAPT_FLAGS := --no-resource-removal
 include $(BUILD_PACKAGE)
diff --git a/core/tests/overlaytests/host/test-apps/UpdateOverlay/Android.mk b/core/tests/overlaytests/host/test-apps/UpdateOverlay/Android.mk
index ab3faf0..8656781 100644
--- a/core/tests/overlaytests/host/test-apps/UpdateOverlay/Android.mk
+++ b/core/tests/overlaytests/host/test-apps/UpdateOverlay/Android.mk
@@ -21,6 +21,8 @@
 LOCAL_SDK_VERSION := current
 LOCAL_COMPATIBILITY_SUITE := general-tests
 LOCAL_STATIC_JAVA_LIBRARIES := android-support-test
+LOCAL_USE_AAPT2 := true
+LOCAL_AAPT_FLAGS := --no-resource-removal
 include $(BUILD_PACKAGE)
 
 my_package_prefix := com.android.server.om.hosttest.framework_overlay
diff --git a/tools/aapt2/cmd/Link.cpp b/tools/aapt2/cmd/Link.cpp
index 20ea3cb6..8666f7b 100644
--- a/tools/aapt2/cmd/Link.cpp
+++ b/tools/aapt2/cmd/Link.cpp
@@ -1775,10 +1775,12 @@
 
     // Before we process anything, remove the resources whose default values don't exist.
     // We want to force any references to these to fail the build.
-    if (!NoDefaultResourceRemover{}.Consume(context_, &final_table_)) {
-      context_->GetDiagnostics()->Error(DiagMessage()
-                                        << "failed removing resources with no defaults");
-      return 1;
+    if (!options_.no_resource_removal) {
+      if (!NoDefaultResourceRemover{}.Consume(context_, &final_table_)) {
+        context_->GetDiagnostics()->Error(DiagMessage()
+                                          << "failed removing resources with no defaults");
+        return 1;
+      }
     }
 
     ReferenceLinker linker;
diff --git a/tools/aapt2/cmd/Link.h b/tools/aapt2/cmd/Link.h
index a42c0f2..950dac20 100644
--- a/tools/aapt2/cmd/Link.h
+++ b/tools/aapt2/cmd/Link.h
@@ -59,6 +59,7 @@
   bool no_version_vectors = false;
   bool no_version_transitions = false;
   bool no_resource_deduping = false;
+  bool no_resource_removal = false;
   bool no_xml_namespaces = false;
   bool do_not_compress_anything = false;
   std::unordered_set<std::string> extensions_to_not_compress;
@@ -136,6 +137,9 @@
     AddOptionalSwitch("--no-resource-deduping", "Disables automatic deduping of resources with\n"
             "identical values across compatible configurations.",
         &options_.no_resource_deduping);
+    AddOptionalSwitch("--no-resource-removal", "Disables automatic removal of resources without\n"
+            "defaults. Use this only when building runtime resource overlay packages.",
+        &options_.no_resource_removal);
     AddOptionalSwitch("--enable-sparse-encoding",
         "This decreases APK size at the cost of resource retrieval performance.",
         &options_.table_flattener_options.use_sparse_entries);
@@ -280,4 +284,4 @@
 
 }// namespace aapt
 
-#endif //AAPT2_LINK_H
\ No newline at end of file
+#endif //AAPT2_LINK_H