Adds droidstubs support to sdk module

Adds stubs_sources property to sdk and unzips the droidstubs srcjar
into the snapshot directory.

Adds an UnzipToSnapshot method to the SnapshotBuilder which creates
a rule that uses zip2zip to repackage the supplied zip content into a
temporary zip file that matches what the required snapshot structure.
e.g. if the supplied zip contains foo/Foo.java and that needs to be in
the snapshot directory java/foo/stubs then it will create a zip that
contains java/foo/stubs/foo/Foo.java.

The temporary zip that is the output of that rule is added to the
zipsToMerge field for merging later.

If the zipsToMerge is empty then the snapshot zip is created as
before. Otherwise, a temporary zip file is created. That is then
merged with the other zip files in zipsToMerge to create the final
snapshot zip.

Adds prebuilt_stubs_sources for use by the generated .bp module.

Bug: 143678475
Test: added conscrypt sdk module and attempted to build it
Change-Id: Ie274263af3a08e36a73c61c0dbf0c341fd6967e2

java/droiddoc.go

@@ -37,6 +37,8 @@ func init() {
 
 	android.RegisterModuleType("droidstubs", DroidstubsFactory)
 	android.RegisterModuleType("droidstubs_host", DroidstubsHostFactory)
+
+	android.RegisterModuleType("prebuilt_stubs_sources", PrebuiltStubsSourcesFactory)
 }
 
 var (
@@ -1163,6 +1165,7 @@ func (d *Droiddoc) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 //
 type Droidstubs struct {
 	Javadoc
+	android.SdkBase
 
 	properties              DroidstubsProperties
 	apiFile                 android.WritablePath
@@ -1208,6 +1211,7 @@ func DroidstubsFactory() android.Module {
 		&module.Javadoc.properties)
 
 	InitDroiddocModule(module, android.HostAndDeviceSupported)
+	android.InitSdkAwareModule(module)
 	return module
 }
 
@@ -1913,3 +1917,88 @@ func zipSyncCmd(ctx android.ModuleContext, rule *android.RuleBuilder,
 func zipSyncCleanupCmd(rule *android.RuleBuilder, srcJarDir android.ModuleOutPath) {
 	rule.Command().Text("rm -rf").Text(srcJarDir.String())
 }
+
+var _ android.PrebuiltInterface = (*PrebuiltStubsSources)(nil)
+
+type PrebuiltStubsSourcesProperties struct {
+	Srcs []string `android:"path"`
+}
+
+type PrebuiltStubsSources struct {
+	android.ModuleBase
+	android.DefaultableModuleBase
+	prebuilt android.Prebuilt
+	android.SdkBase
+
+	properties PrebuiltStubsSourcesProperties
+
+	srcs        android.Paths
+	stubsSrcJar android.ModuleOutPath
+}
+
+func (p *PrebuiltStubsSources) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	p.srcs = android.PathsForModuleSrc(ctx, p.properties.Srcs)
+}
+
+func (p *PrebuiltStubsSources) Prebuilt() *android.Prebuilt {
+	return &p.prebuilt
+}
+
+func (p *PrebuiltStubsSources) Name() string {
+	return p.prebuilt.Name(p.ModuleBase.Name())
+}
+
+func (p *PrebuiltStubsSources) Srcs() android.Paths {
+	return append(android.Paths{}, p.srcs...)
+}
+
+// prebuilt_stubs_sources imports a set of java source files as if they were
+// generated by droidstubs.
+//
+// By default, a prebuilt_stubs_sources has a single variant that expects a
+// set of `.java` files generated by droidstubs.
+//
+// Specifying `host_supported: true` will produce two variants, one for use as a dependency of device modules and one
+// for host modules.
+//
+// Intended only for use by sdk snapshots.
+func PrebuiltStubsSourcesFactory() android.Module {
+	module := &PrebuiltStubsSources{}
+
+	module.AddProperties(&module.properties)
+
+	android.InitPrebuiltModule(module, &module.properties.Srcs)
+	android.InitSdkAwareModule(module)
+	InitDroiddocModule(module, android.HostAndDeviceSupported)
+	return module
+}
+
+func (d *Droidstubs) BuildSnapshot(sdkModuleContext android.ModuleContext, builder android.SnapshotBuilder) {
+	stubsSrcJar := d.stubsSrcJar
+
+	snapshotRelativeDir := filepath.Join("java", d.Name()+"_stubs_sources")
+	builder.UnzipToSnapshot(stubsSrcJar, snapshotRelativeDir)
+
+	name := d.Name()
+	bp := builder.AndroidBpFile()
+	bp.Printfln("prebuilt_stubs_sources {")
+	bp.Indent()
+	bp.Printfln("name: %q,", builder.VersionedSdkMemberName(name))
+	bp.Printfln("sdk_member_name: %q,", name)
+	bp.Printfln("srcs: [%q],", snapshotRelativeDir)
+	bp.Dedent()
+	bp.Printfln("}")
+	bp.Printfln("")
+
+	// This module is for the case when the source tree for the unversioned module
+	// doesn't exist (i.e. building in an unbundled tree). "prefer:" is set to false
+	// so that this module does not eclipse the unversioned module if it exists.
+	bp.Printfln("prebuilt_stubs_sources {")
+	bp.Indent()
+	bp.Printfln("name: %q,", name)
+	bp.Printfln("srcs: [%q],", snapshotRelativeDir)
+	bp.Printfln("prefer: false,")
+	bp.Dedent()
+	bp.Printfln("}")
+	bp.Printfln("")
+}