Add a Tag field to dist to dist a tagged output

Make java_library support this mode of output, to allow
callers to dist the classes.jar file rather than the dexed
jar file.

Bug: 152618077
Test: followup CL
Change-Id: I5ba6949833a0fbb95376142aec5096ff5f084c00
Merged-In: I5ba6949833a0fbb95376142aec5096ff5f084c00
(cherry picked from commit 1e65f94a4b2cc7dea1896937c2068b87c899c465)
diff --git a/java/java.go b/java/java.go
index 7645d85..9a9a02f 100644
--- a/java/java.go
+++ b/java/java.go
@@ -421,6 +421,8 @@
 
 	// list of the xref extraction files
 	kytheFiles android.Paths
+
+	distFile android.Path
 }
 
 func (j *Module) OutputFiles(tag string) (android.Paths, error) {
@@ -1778,9 +1780,18 @@
 // Java libraries (.jar file)
 //
 
+type LibraryProperties struct {
+	Dist struct {
+		// The tag of the output of this module that should be output.
+		Tag *string `android:"arch_variant"`
+	} `android:"arch_variant"`
+}
+
 type Library struct {
 	Module
 
+	libraryProperties LibraryProperties
+
 	InstallMixin func(ctx android.ModuleContext, installPath android.Path) (extraInstallDeps android.Paths)
 }
 
@@ -1824,6 +1835,15 @@
 		j.installFile = ctx.InstallFile(android.PathForModuleInstall(ctx, "framework"),
 			ctx.ModuleName()+".jar", j.outputFile, extraInstallDeps...)
 	}
+
+	// Verify Dist.Tag is set to a supported output
+	if j.libraryProperties.Dist.Tag != nil {
+		distFiles, err := j.OutputFiles(*j.libraryProperties.Dist.Tag)
+		if err != nil {
+			ctx.PropertyErrorf("dist.tag", "%s", err.Error())
+		}
+		j.distFile = distFiles[0]
+	}
 }
 
 func (j *Library) DepsMutator(ctx android.BottomUpMutatorContext) {
@@ -1944,7 +1964,8 @@
 		&module.Module.properties,
 		&module.Module.deviceProperties,
 		&module.Module.dexpreoptProperties,
-		&module.Module.protoProperties)
+		&module.Module.protoProperties,
+		&module.libraryProperties)
 
 	android.InitApexModule(module)
 	android.InitSdkAwareModule(module)