Add tradefed_java_library_host

Add a module type for tradefed libraries that causes an additional
copy to be installed at out/host/linux-x86/tradefed.

Bug: 122332235
Bug: 141877526
Test: m tradefed
Change-Id: Ib7160dd060ad83d2dfb81d6a7106cb0dac98553e
diff --git a/java/tradefed.go b/java/tradefed.go
new file mode 100644
index 0000000..ebbdec1
--- /dev/null
+++ b/java/tradefed.go
@@ -0,0 +1,37 @@
+// Copyright 2019 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package java
+
+import (
+	"android/soong/android"
+)
+
+func init() {
+	android.RegisterModuleType("tradefed_java_library_host", tradefedJavaLibraryFactory)
+}
+
+// tradefed_java_library_factory wraps java_library and installs an additional
+// copy of the output jar to $HOST_OUT/tradefed.
+func tradefedJavaLibraryFactory() android.Module {
+	module := LibraryHostFactory().(*Library)
+	module.InstallMixin = tradefedJavaLibraryInstall
+	return module
+}
+
+func tradefedJavaLibraryInstall(ctx android.ModuleContext, path android.Path) android.Paths {
+	installedPath := ctx.InstallFile(android.PathForModuleInstall(ctx, "tradefed"),
+		ctx.ModuleName()+".jar", path)
+	return android.Paths{installedPath}
+}