Dexpreopt standalone system server jars from prebuilts.

This change adds support for dexpreopting standalone system server
jars from prebuilts.

Bug: 203198541
Test: -
  1. Add a standalone system server jar (e.g., by patching
     aosp/1906158)
  2. Build and drop a module SDK and an APEX.
  3. Build a system image from prebuilts.
  4. See the odex and vdex files generated in
     $ANDROID_PRODUCT_OUT/system/framework/oat/
Change-Id: I8f4eaed10a1053cd560b8583efa12dc495f58db1

java/androidmk.go

@@ -182,7 +182,14 @@ func (j *TestHelperLibrary) AndroidMkEntries() []android.AndroidMkEntries {
 }
 
 func (prebuilt *Import) AndroidMkEntries() []android.AndroidMkEntries {
-	if prebuilt.hideApexVariantFromMake || !prebuilt.ContainingSdk().Unversioned() {
+	if prebuilt.hideApexVariantFromMake {
+		// For a library imported from a prebuilt APEX, we don't need a Make module for itself, as we
+		// don't need to install it. However, we need to add its dexpreopt outputs as sub-modules, if it
+		// is preopted.
+		dexpreoptEntries := prebuilt.dexpreopter.AndroidMkEntriesForApex()
+		return append(dexpreoptEntries, android.AndroidMkEntries{Disabled: true})
+	}
+	if !prebuilt.ContainingSdk().Unversioned() {
 		return []android.AndroidMkEntries{android.AndroidMkEntries{
 			Disabled: true,
 		}}

java/dexpreopt.go

@@ -115,6 +115,11 @@ func isApexVariant(ctx android.BaseModuleContext) bool {
 	return !apexInfo.IsForPlatform()
 }
 
+func forPrebuiltApex(ctx android.BaseModuleContext) bool {
+	apexInfo := ctx.Provider(android.ApexInfoProvider).(android.ApexInfo)
+	return apexInfo.ForPrebuiltApex
+}
+
 func moduleName(ctx android.BaseModuleContext) string {
 	// Remove the "prebuilt_" prefix if the module is from a prebuilt because the prefix is not
 	// expected by dexpreopter.
@@ -134,7 +139,9 @@ func (d *dexpreopter) dexpreoptDisabled(ctx android.BaseModuleContext) bool {
 		return true
 	}
 
-	if !ctx.Module().(DexpreopterInterface).IsInstallable() {
+	// If the module is from a prebuilt APEX, it shouldn't be installable, but it can still be
+	// dexpreopted.
+	if !ctx.Module().(DexpreopterInterface).IsInstallable() && !forPrebuiltApex(ctx) {
 		return true
 	}