Add a new platform_bootclasspath module type

Initially, this is just a placeholder but functionality will be added
in follow up changes.

Bug: 177892522
Test: m nothing
Change-Id: I890b0d5a117c51a19c9ac5df98c766761d3aa16c
diff --git a/java/platform_bootclasspath.go b/java/platform_bootclasspath.go
new file mode 100644
index 0000000..5507077
--- /dev/null
+++ b/java/platform_bootclasspath.go
@@ -0,0 +1,74 @@
+// Copyright 2021 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"
+	"android/soong/dexpreopt"
+)
+
+func init() {
+	registerPlatformBootclasspathBuildComponents(android.InitRegistrationContext)
+}
+
+func registerPlatformBootclasspathBuildComponents(ctx android.RegistrationContext) {
+	ctx.RegisterModuleType("platform_bootclasspath", platformBootclasspathFactory)
+}
+
+type platformBootclasspathModule struct {
+	android.ModuleBase
+}
+
+func platformBootclasspathFactory() android.Module {
+	m := &platformBootclasspathModule{}
+	android.InitAndroidArchModule(m, android.DeviceSupported, android.MultilibCommon)
+	return m
+}
+
+func (b *platformBootclasspathModule) DepsMutator(ctx android.BottomUpMutatorContext) {
+	if SkipDexpreoptBootJars(ctx) {
+		return
+	}
+
+	// Add a dependency onto the dex2oat tool which is needed for creating the boot image. The
+	// path is retrieved from the dependency by GetGlobalSoongConfig(ctx).
+	dexpreopt.RegisterToolDeps(ctx)
+}
+
+func (b *platformBootclasspathModule) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	// Nothing to do if skipping the dexpreopt of boot image jars.
+	if SkipDexpreoptBootJars(ctx) {
+		return
+	}
+
+	// Force the GlobalSoongConfig to be created and cached for use by the dex_bootjars
+	// GenerateSingletonBuildActions method as it cannot create it for itself.
+	dexpreopt.GetGlobalSoongConfig(ctx)
+
+	imageConfig := b.getImageConfig(ctx)
+	if imageConfig == nil {
+		return
+	}
+
+	// Construct the boot image info from the config.
+	info := BootImageInfo{imageConfig: imageConfig}
+
+	// Make it available for other modules.
+	ctx.SetProvider(BootImageInfoProvider, info)
+}
+
+func (b *platformBootclasspathModule) getImageConfig(ctx android.EarlyModuleContext) *bootImageConfig {
+	return defaultBootImageConfig(ctx)
+}