Merge changes I9b67fd2a,I761f2d06

* changes:
  Revert "Revert "Use AAPT2 by default""
  Work around incorrect R8 proguard compatibility

core/force_aapt2.mk

@@ -17,7 +17,7 @@
 # Including this makefile will force AAPT2 on if FORCE_AAPT2==true,
 # rewriting some properties to convert standard AAPT usage to AAPT2.
 
-ifeq ($(FORCE_AAPT2),true)
+ifneq ($(FORCE_AAPT2),false)
   ifeq ($(LOCAL_USE_AAPT2),)
     # Force AAPT2 on
     LOCAL_USE_AAPT2 := true
@@ -47,7 +47,6 @@ ifeq ($(FORCE_AAPT2),true)
     ifeq (,$(strip $(LOCAL_MANIFEST_FILE)$(LOCAL_FULL_MANIFEST_FILE)))
       ifeq (,$(wildcard $(LOCAL_PATH)/AndroidManifest.xml))
         # work around missing manifests by creating a default one
-        $(call pretty-warning, Missing manifest file)
         LOCAL_FULL_MANIFEST_FILE := $(call local-intermediates-dir,COMMON)/DefaultManifest.xml
         ifdef LOCAL_MIN_SDK_VERSION
           my_manifest_min_sdk_version := $(LOCAL_MIN_SDK_VERSION)

core/java.mk

@@ -458,6 +458,9 @@ endif
 ifeq ($(filter obfuscation,$(LOCAL_PROGUARD_ENABLED)),)
 # By default no obfuscation
 common_proguard_flags += -dontobfuscate
+# Workaround for b/80081393: R8 discards other attributes when
+# -keepattributes *Annotations* is used, even when obfuscation is off.
+common_proguard_flags += -keepattributes '*'
 endif  # No obfuscation
 ifeq ($(filter optimization,$(LOCAL_PROGUARD_ENABLED)),)
 # By default no optimization