Make the srcjar for bcp available in OutputFiles

This makes it possible for Android.bp files to depends on the srcjar.

Bug: 151360309
Test: m platform-bootclasspath.srcjar
Change-Id: Id42cc3cff89c084b55c7fb0726ad84ecd4f50f58
diff --git a/java/platform_bootclasspath.go b/java/platform_bootclasspath.go
index bab0bf6..02a2298 100644
--- a/java/platform_bootclasspath.go
+++ b/java/platform_bootclasspath.go
@@ -57,6 +57,9 @@
 
 	// Path to the monolithic hiddenapi-unsupported.csv file.
 	hiddenAPIMetadataCSV android.OutputPath
+
+	// Path to a srcjar containing all the transitive sources of the bootclasspath.
+	srcjar android.OutputPath
 }
 
 type platformBootclasspathProperties struct {
@@ -95,6 +98,8 @@
 		return android.Paths{b.hiddenAPIIndexCSV}, nil
 	case "hiddenapi-metadata.csv":
 		return android.Paths{b.hiddenAPIMetadataCSV}, nil
+	case ".srcjar":
+		return android.Paths{b.srcjar}, nil
 	}
 
 	return nil, fmt.Errorf("unknown tag %s", tag)
@@ -182,8 +187,8 @@
 	}
 	jarArgs := resourcePathsToJarArgs(transitiveSrcFiles)
 	jarArgs = append(jarArgs, "-srcjar") // Move srcfiles to the right package
-	transitiveSrcJar := android.PathForModuleOut(ctx, ctx.ModuleName()+"-transitive.srcjar")
-	TransformResourcesToJar(ctx, transitiveSrcJar, jarArgs, transitiveSrcFiles)
+	b.srcjar = android.PathForModuleOut(ctx, ctx.ModuleName()+"-transitive.srcjar").OutputPath
+	TransformResourcesToJar(ctx, b.srcjar, jarArgs, transitiveSrcFiles)
 
 	// Gather all the fragments dependencies.
 	b.fragments = gatherApexModulePairDepsWithTag(ctx, bootclasspathFragmentDepTag)