libchrome: Create a soong plugin to clean up source/header generation

This change adds a soong plugin that significantly cleans up the
generation of source/header files from .mojom files.

Bug: 109924413
Test: m
Change-Id: Ic2cf32f1bb914f826eee4c8559285e0ed4e23ced

4 files changed, 521 insertions, 129 deletions

diff --git a/Android.bp b/Android.bp
index 051e18eca7..4dd1aa904e 100644
--- a/Android.bp
+++ b/Android.bp
@@ -685,12 +685,44 @@ python_binary_host {
     defaults: ["libmojo_scripts"],
 }
 
+python_binary_host {
+    name: "merge_srcjars",
+    main: "libchrome_tools/merge_srcjars.py",
+    srcs: ["libchrome_tools/merge_srcjars.py"],
+    version: {
+        py3: {
+            enabled: true,
+        },
+        py2: {
+            enabled: false,
+        },
+    },
+}
+
+// TODO(lhchavez): Delete this once all other projects have been migrated.
 cc_prebuilt_binary {
     name: "mojom_source_generator_sh",
     srcs: ["libchrome_tools/mojom_source_generator.sh"],
     host_supported: true,
 }
 
+genrule {
+    name: "libmojo_mojom_templates",
+    cmd: "$(location mojom_bindings_generator)" +
+    "    --use_bundled_pylibs precompile" +
+    "    -o $(genDir)",
+
+    tools: [
+        "mojom_bindings_generator",
+    ],
+
+    out: [
+        "cpp_templates.zip",
+        "java_templates.zip",
+        "js_templates.zip",
+    ],
+}
+
 python_binary_host {
     name: "mojom_generate_type_mappings",
     main: "libchrome_tools/mojom_generate_type_mappings.py",
@@ -723,115 +755,27 @@ genrule {
     out: ["common_custom_types__type_mappings"],
 }
 
-genrule {
-    name: "libmojo_mojom_headers",
-    cmd: "$(location mojom_source_generator_sh)" +
-    "    --mojom_bindings_generator=$(location mojom_bindings_generator)" +
-    "    --package=external/libchrome" +
-    "    --output_dir=$(genDir)" +
-    "    --bytecode_path=$(genDir)" +
-    "    --typemap=$(location common_custom_types__type_mappings)" +
-    "    --generators=c++" +
-    "    --use_new_wrapper_types" +
-    "    $(in)",
-
-    tools: [
-        "mojom_bindings_generator",
-        "mojom_source_generator_sh",
-    ],
-
-    tool_files: [":libmojo_common_custom_types__type_mappings"],
-
+generate_mojom_pickles {
+    name: "libmojo_mojom_pickles",
     srcs: [":libmojo_mojom_files"],
+}
 
-    out: [
-        "ipc/ipc.mojom.h",
-        "ipc/ipc.mojom-shared.h",
-        "ipc/ipc.mojom-shared-internal.h",
-        "mojo/common/file.mojom.h",
-        "mojo/common/file.mojom-shared.h",
-        "mojo/common/file.mojom-shared-internal.h",
-        "mojo/common/file_path.mojom.h",
-        "mojo/common/file_path.mojom-shared.h",
-        "mojo/common/file_path.mojom-shared-internal.h",
-        "mojo/common/string16.mojom.h",
-        "mojo/common/string16.mojom-shared.h",
-        "mojo/common/string16.mojom-shared-internal.h",
-        "mojo/common/text_direction.mojom.h",
-        "mojo/common/text_direction.mojom-shared.h",
-        "mojo/common/text_direction.mojom-shared-internal.h",
-        "mojo/common/time.mojom.h",
-        "mojo/common/time.mojom-shared.h",
-        "mojo/common/time.mojom-shared-internal.h",
-        "mojo/common/unguessable_token.mojom.h",
-        "mojo/common/unguessable_token.mojom-shared.h",
-        "mojo/common/unguessable_token.mojom-shared-internal.h",
-        "mojo/common/values.mojom.h",
-        "mojo/common/values.mojom-shared.h",
-        "mojo/common/values.mojom-shared-internal.h",
-        "mojo/common/version.mojom.h",
-        "mojo/common/version.mojom-shared.h",
-        "mojo/common/version.mojom-shared-internal.h",
-        "mojo/public/interfaces/bindings/interface_control_messages.mojom.h",
-        "mojo/public/interfaces/bindings/interface_control_messages.mojom-shared.h",
-        "mojo/public/interfaces/bindings/interface_control_messages.mojom-shared-internal.h",
-        "mojo/public/interfaces/bindings/pipe_control_messages.mojom.h",
-        "mojo/public/interfaces/bindings/pipe_control_messages.mojom-shared.h",
-        "mojo/public/interfaces/bindings/pipe_control_messages.mojom-shared-internal.h",
-        "ui/gfx/geometry/mojo/geometry.mojom.h",
-        "ui/gfx/geometry/mojo/geometry.mojom-shared.h",
-        "ui/gfx/geometry/mojo/geometry.mojom-shared-internal.h",
-        "ui/gfx/range/mojo/range.mojom.h",
-        "ui/gfx/range/mojo/range.mojom-shared.h",
-        "ui/gfx/range/mojo/range.mojom-shared-internal.h",
-    ],
+generate_mojom_headers {
+    name: "libmojo_mojom_headers",
+    srcs: [":libmojo_mojom_files"],
+    pickles: [":libmojo_mojom_pickles"],
+    templates: ":libmojo_mojom_templates",
+    flags: "--disallow_native_types",
+    typemaps: [":libmojo_common_custom_types__type_mappings"],
 }
 
-genrule {
+generate_mojom_srcs {
     name: "libmojo_mojom_srcs",
-    cmd: "$(location mojom_source_generator_sh)" +
-    "    --mojom_bindings_generator=$(location mojom_bindings_generator)" +
-    "    --package=external/libchrome" +
-    "    --output_dir=$(genDir)" +
-    "    --bytecode_path=$(genDir)" +
-    "    --typemap=$(location common_custom_types__type_mappings)" +
-    "    --generators=c++" +
-    "    --use_new_wrapper_types" +
-    "    $(in)",
-
-    tools: [
-        "mojom_bindings_generator",
-        "mojom_source_generator_sh",
-    ],
-
-    tool_files: [":libmojo_common_custom_types__type_mappings"],
-
     srcs: [":libmojo_mojom_files"],
-
-    out: [
-        "ipc/ipc.mojom.cc",
-        "ipc/ipc.mojom-shared.cc",
-        "mojo/common/file.mojom.cc",
-        "mojo/common/file.mojom-shared.cc",
-        "mojo/common/string16.mojom.cc",
-        "mojo/common/string16.mojom-shared.cc",
-        "mojo/common/text_direction.mojom.cc",
-        "mojo/common/text_direction.mojom-shared.cc",
-        "mojo/common/time.mojom.cc",
-        "mojo/common/time.mojom-shared.cc",
-        "mojo/common/unguessable_token.mojom.cc",
-        "mojo/common/unguessable_token.mojom-shared.cc",
-        "mojo/common/version.mojom.cc",
-        "mojo/common/version.mojom-shared.cc",
-        "mojo/public/interfaces/bindings/interface_control_messages.mojom.cc",
-        "mojo/public/interfaces/bindings/interface_control_messages.mojom-shared.cc",
-        "mojo/public/interfaces/bindings/pipe_control_messages.mojom.cc",
-        "mojo/public/interfaces/bindings/pipe_control_messages.mojom-shared.cc",
-        "ui/gfx/geometry/mojo/geometry.mojom.cc",
-        "ui/gfx/geometry/mojo/geometry.mojom-shared.cc",
-        "ui/gfx/range/mojo/range.mojom.cc",
-        "ui/gfx/range/mojo/range.mojom-shared.cc",
-    ],
+    pickles: [":libmojo_mojom_pickles"],
+    templates: ":libmojo_mojom_templates",
+    flags: "--disallow_native_types",
+    typemaps: [":libmojo_common_custom_types__type_mappings"],
 }
 
 // TODO(hidehiko): Remove JNI for ContextUtils, after cleaning up the
@@ -875,15 +819,11 @@ cc_library_shared {
     name: "libmojo",
     vendor_available: true,
 
+    generated_sources: ["libmojo_mojom_srcs"],
     generated_headers: [
         "libmojo_jni_headers",
         "libmojo_mojom_headers",
     ],
-
-    generated_sources: [
-        "libmojo_mojom_srcs",
-    ],
-
     export_generated_headers: [
         "libmojo_jni_headers",
         "libmojo_mojom_headers",
@@ -936,29 +876,14 @@ cc_library_shared {
     export_include_dirs: ["."],
 }
 
-genrule {
+generate_mojom_srcjar {
     name: "libmojo_mojom_java_srcs",
-    cmd: "$(location mojom_source_generator_sh)" +
-    "    --mojom_bindings_generator=$(location mojom_bindings_generator)" +
-    "    --package=external/libchrome" +
-    "    --output_dir=$(genDir)" +
-    "    --bytecode_path=$(genDir)" +
-    "    --typemap=$(location common_custom_types__type_mappings)" +
-    "    --generators=java" +
-    "    --use_new_wrapper_types" +
-    "    --srcjar=$(out)" +
-    "    $(in)",
-
-    tools: [
-        "mojom_bindings_generator",
-        "mojom_source_generator_sh",
-    ],
-
-    tool_files: [":libmojo_common_custom_types__type_mappings"],
-
     srcs: [":libmojo_mojom_files"],
-
-    out: ["libmojo_mojom.srcjar"],
+    pickles: [":libmojo_mojom_pickles"],
+    srcjar: "libmojo_mojom.srcjar",
+    templates: ":libmojo_mojom_templates",
+    flags: "--disallow_native_types",
+    typemaps: [":libmojo_common_custom_types__type_mappings"],
 }
 
 java_library {
diff --git a/libchrome_tools/merge_srcjars.py b/libchrome_tools/merge_srcjars.py
new file mode 100755
index 0000000000..f774764087
--- /dev/null
+++ b/libchrome_tools/merge_srcjars.py
@@ -0,0 +1,26 @@
+#!/usr/bin/env python3
+
+"""Merges several .srcjar files."""
+
+import argparse
+import zipfile
+
+
+def _main():
+    parser = argparse.ArgumentParser(description="Merge several .srcjar files")
+    parser.add_argument("--output", type=argparse.FileType("wb"),
+                        help="The path of the output .srcjar")
+    parser.add_argument("srcjar", metavar="SRCJAR", type=argparse.FileType("rb"),
+                        nargs="+",
+                        help="The path of the .srcjar files to merge")
+    args = parser.parse_args()
+
+    with zipfile.ZipFile(args.output, "w") as output:
+        for srcjar_path in args.srcjar:
+            with zipfile.ZipFile(srcjar_path, "r") as srcjar:
+                for path in srcjar.namelist():
+                    output.writestr(path, srcjar.read(path))
+
+
+if __name__ == "__main__":
+    _main()
diff --git a/soong/Android.bp b/soong/Android.bp
new file mode 100644
index 0000000000..7230b812d2
--- /dev/null
+++ b/soong/Android.bp
@@ -0,0 +1,14 @@
+bootstrap_go_package {
+    name: "soong-libchrome",
+    pkgPath: "android/soong/external/libchrome",
+    deps: [
+        "blueprint",
+        "soong",
+        "soong-android",
+        "soong-genrule",
+    ],
+    srcs: [
+        "bindings_generator.go",
+    ],
+    pluginFor: ["soong_build"],
+}
diff --git a/soong/bindings_generator.go b/soong/bindings_generator.go
new file mode 100644
index 0000000000..36462cb036
--- /dev/null
+++ b/soong/bindings_generator.go
@@ -0,0 +1,427 @@
+package libchrome
+
+import (
+	"fmt"
+	"path"
+	"path/filepath"
+	"strings"
+
+	"android/soong/android"
+	"android/soong/genrule"
+
+	"github.com/google/blueprint"
+)
+
+func init() {
+	android.RegisterModuleType("generate_mojom_pickles", mojomPicklesFactory)
+	android.RegisterModuleType("generate_mojom_headers", mojomHeadersFactory)
+	android.RegisterModuleType("generate_mojom_srcs", mojomSrcsFactory)
+	android.RegisterModuleType("generate_mojom_srcjar", mojomSrcjarFactory)
+}
+
+var (
+	pctx = android.NewPackageContext("android/soong/external/libchrome")
+
+	mojomBindingsGenerator = pctx.HostBinToolVariable("mojomBindingsGenerator", "mojom_bindings_generator")
+	mergeSrcjars           = pctx.HostBinToolVariable("mergeSrcjars", "merge_srcjars")
+
+	generateMojomPicklesRule = pctx.StaticRule("generateMojomPicklesRule", blueprint.RuleParams{
+		Command: `${mojomBindingsGenerator}
+		--use_bundled_pylibs parse
+		-d ${package}
+		${flags}
+		-o ${outDir}
+		${in}`,
+		CommandDeps: []string{
+			"${mojomBindingsGenerator}",
+		},
+		Description: "Mojo pickles generation $in => $out",
+	}, "package", "flags", "outDir")
+
+	generateMojomSrcsRule = pctx.StaticRule("generateMojomSrcsRule", blueprint.RuleParams{
+		Command: `${mojomBindingsGenerator}
+		--use_bundled_pylibs generate
+		-o ${outDir}
+		-I=${package}:${package}
+		-d ${package}
+		${flags}
+		--bytecode_path=${templateDir}
+		--generators=${generator}
+		--use_new_wrapper_types
+		${in}`,
+		CommandDeps: []string{
+			"${mojomBindingsGenerator}",
+		},
+		Description: "Mojo sources generation $in => $out",
+	}, "generator", "package", "flags", "outDir", "templateDir")
+
+	mergeSrcjarsRule = pctx.StaticRule("mergeSrcjarsRule", blueprint.RuleParams{
+		Command: "${mergeSrcjars} --output=${out} ${in}",
+		CommandDeps: []string{
+			"${mergeSrcjars}",
+		},
+		Description: "Merge .srcjars $in => $out",
+	})
+)
+
+type mojomPicklesProperties struct {
+	// list of input files
+	Srcs []string
+}
+
+type mojomPickles struct {
+	android.ModuleBase
+
+	properties mojomPicklesProperties
+
+	generatedSrcs android.Paths
+	outDir        android.Path
+}
+
+var _ genrule.SourceFileGenerator = (*mojomPickles)(nil)
+
+func (m *mojomPickles) DepsMutator(ctx android.BottomUpMutatorContext) {
+	android.ExtractSourcesDeps(ctx, m.properties.Srcs)
+}
+
+func (m *mojomPickles) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	m.outDir = android.PathForModuleGen(ctx, "")
+	// TODO(lhchavez): Actually make this generate files once libchrome
+	// roll progresses.
+}
+
+func (m *mojomPickles) GeneratedHeaderDirs() android.Paths {
+	return nil
+}
+
+func (m *mojomPickles) GeneratedDeps() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func (m *mojomPickles) GeneratedSourceFiles() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func (m *mojomPickles) Srcs() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func mojomPicklesFactory() android.Module {
+	m := &mojomPickles{}
+	m.AddProperties(&m.properties)
+	android.InitAndroidModule(m)
+	return m
+}
+
+// mojomGenerationProperties are the common properties across the header,
+// source and Java source modules.
+type mojomGenerationProperties struct {
+	// list of input files
+	Srcs []string
+
+	// name of the output .srcjar
+	Srcjar string
+
+	// name of the templates module
+	Templates string
+
+	// Additional flags to pass to the bindings generation script
+	Flags string
+
+	// list of pickles modules that will be imported
+	Pickles []string
+
+	// list of include paths
+	Includes []string
+
+	// list of typemaps modules that will be imported
+	Typemaps []string
+}
+
+// extractSources adds any necessary dependencies to satisfy filegroup or
+// generated sources modules listed in the properties using ":module" syntax,
+// if any.
+func (p *mojomGenerationProperties) extractSources(ctx android.BottomUpMutatorContext) {
+	android.ExtractSourcesDeps(ctx, p.Srcs)
+	android.ExtractSourcesDeps(ctx, p.Typemaps)
+	android.ExtractSourcesDeps(ctx, p.Pickles)
+	android.ExtractSourceDeps(ctx, &p.Templates)
+}
+
+// flags generates all needed flags for the build rule.
+func (p *mojomGenerationProperties) flags(ctx android.ModuleContext) string {
+	flags := []string{}
+
+	for _, typemap := range ctx.ExpandSources(p.Typemaps, nil) {
+		flags = append(flags, fmt.Sprintf("--typemap=%s", typemap.String()))
+	}
+	for _, include := range p.Includes {
+		includePath, err := filepath.Abs(include)
+		if err != nil {
+			ctx.PropertyErrorf("includes", "Failed to get the absolute path for %s: %q", include, err)
+		}
+		flags = append(flags, fmt.Sprintf("-I=%s:%s", includePath, includePath))
+	}
+	for _, pickle := range p.Pickles {
+		m := android.SrcIsModule(pickle)
+		if m == "" {
+			ctx.PropertyErrorf("pickles", "not a module: %q", m)
+			continue
+		}
+		module := ctx.GetDirectDepWithTag(m, android.SourceDepTag).(*mojomPickles)
+		flags = append(flags, fmt.Sprintf("--gen_dir=%s", module.outDir.String()))
+	}
+	if p.Flags != "" {
+		flags = append(flags, p.Flags)
+	}
+
+	return strings.Join(flags, " ")
+}
+
+// implicitDeps collects all dependencies of the module.
+func (p *mojomGenerationProperties) implicitDeps(ctx android.ModuleContext) android.Paths {
+	deps := android.Paths{}
+	deps = append(deps, ctx.ExpandSources(p.Pickles, nil)...)
+	deps = append(deps, ctx.ExpandSources(p.Typemaps, nil)...)
+	deps = append(deps, ctx.ExpandSources([]string{p.Templates}, nil)...)
+	return deps
+}
+
+// templateDir returns the path where the template .zips are located.
+func (p *mojomGenerationProperties) templateDir(ctx android.ModuleContext) string {
+	srcFiles := ctx.ExpandSources([]string{p.Templates}, nil)
+	if len(srcFiles) == 0 {
+		ctx.PropertyErrorf("templates", "module %s does not produce any files", p.Templates)
+		return ""
+	}
+	return path.Dir(srcFiles[0].String())
+}
+
+// mojomSrcsRuleDescription has the necessary arguments to perform one
+// invocation of generateMojomSrcsRule.
+type mojomSrcsRuleDescription struct {
+	generatedExtensions []string
+	extraFlags          string
+}
+
+// generateBuildActions generates all the necessary build actions for the
+// current module.
+func (p *mojomGenerationProperties) generateBuildActions(
+	ctx android.ModuleContext,
+	generator string,
+	descriptions []mojomSrcsRuleDescription,
+) android.Paths {
+	packageName := android.PathForModuleSrc(ctx, "").Rel()
+	outDir := android.PathForModuleGen(ctx, "")
+	implicitDeps := p.implicitDeps(ctx)
+	templateDir := p.templateDir(ctx)
+	generatedSrcs := android.Paths{}
+
+	for _, in := range ctx.ExpandSources(p.Srcs, nil) {
+		if !strings.HasSuffix(in.Rel(), ".mojom") {
+			ctx.PropertyErrorf("srcs", "Source is not a .mojom file: %s", in.Rel())
+			continue
+		}
+		relStem := strings.TrimSuffix(in.Rel(), ".mojom")
+
+		for _, description := range descriptions {
+			outs := android.WritablePaths{}
+			for _, ext := range description.generatedExtensions {
+				out := android.PathForModuleGen(ctx, relStem+ext)
+				outs = append(outs, out)
+				generatedSrcs = append(generatedSrcs, out)
+			}
+			ctx.ModuleBuild(pctx, android.ModuleBuildParams{
+				Rule:      generateMojomSrcsRule,
+				Input:     in,
+				Implicits: implicitDeps,
+				Outputs:   outs,
+				Args: map[string]string{
+					"generator":   generator,
+					"package":     packageName,
+					"flags":       fmt.Sprintf("%s %s", p.flags(ctx), description.extraFlags),
+					"outDir":      outDir.String(),
+					"templateDir": templateDir,
+				},
+			})
+		}
+	}
+
+	return generatedSrcs
+}
+
+// mojomHeaders generates all the .h files for a .mojom source.
+type mojomHeaders struct {
+	android.ModuleBase
+
+	properties mojomGenerationProperties
+
+	exportedHeaderDirs android.Paths
+	generatedSrcs      android.Paths
+}
+
+var _ genrule.SourceFileGenerator = (*mojomHeaders)(nil)
+
+func (m *mojomHeaders) DepsMutator(ctx android.BottomUpMutatorContext) {
+	m.properties.extractSources(ctx)
+}
+
+func (m *mojomHeaders) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	m.generatedSrcs = m.properties.generateBuildActions(
+		ctx,
+		"c++",
+		[]mojomSrcsRuleDescription{
+			{
+				generatedExtensions: []string{".mojom.h"},
+				extraFlags:          "",
+			},
+			{
+				generatedExtensions: []string{".mojom-shared.h", ".mojom-shared-internal.h"},
+				extraFlags:          "--generate_non_variant_code",
+			},
+			{
+				generatedExtensions: []string{".mojom-shared-message-ids.h"},
+				extraFlags:          "--generate_message_ids --generate_non_variant_code",
+			},
+		},
+	)
+	m.exportedHeaderDirs = append(m.exportedHeaderDirs, android.PathForModuleGen(ctx, ""))
+}
+
+func (m *mojomHeaders) GeneratedHeaderDirs() android.Paths {
+	return m.exportedHeaderDirs
+}
+
+func (m *mojomHeaders) GeneratedDeps() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func (m *mojomHeaders) GeneratedSourceFiles() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func (m *mojomHeaders) Srcs() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func mojomHeadersFactory() android.Module {
+	m := &mojomHeaders{}
+	m.AddProperties(&m.properties)
+	android.InitAndroidModule(m)
+	return m
+}
+
+// mojomHeaders generates all the .cc files for a .mojom source.
+type mojomSrcs struct {
+	android.ModuleBase
+
+	properties mojomGenerationProperties
+
+	generatedSrcs android.Paths
+}
+
+var _ genrule.SourceFileGenerator = (*mojomSrcs)(nil)
+
+func (m *mojomSrcs) DepsMutator(ctx android.BottomUpMutatorContext) {
+	m.properties.extractSources(ctx)
+}
+
+func (m *mojomSrcs) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	m.generatedSrcs = m.properties.generateBuildActions(
+		ctx,
+		"c++",
+		[]mojomSrcsRuleDescription{
+			{
+				generatedExtensions: []string{".mojom.cc"},
+				extraFlags:          "",
+			},
+			{
+				generatedExtensions: []string{".mojom-shared.cc"},
+				extraFlags:          "--generate_non_variant_code",
+			},
+		},
+	)
+}
+
+func (m *mojomSrcs) GeneratedHeaderDirs() android.Paths {
+	return nil
+}
+
+func (m *mojomSrcs) GeneratedDeps() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func (m *mojomSrcs) GeneratedSourceFiles() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func (m *mojomSrcs) Srcs() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func mojomSrcsFactory() android.Module {
+	m := &mojomSrcs{}
+	m.AddProperties(&m.properties)
+	android.InitAndroidModule(m)
+	return m
+}
+
+// mojomHeaders generates the .srcjar file for a set of .mojom source.
+type mojomSrcjar struct {
+	android.ModuleBase
+
+	properties mojomGenerationProperties
+
+	outDir        android.Path
+	generatedSrcs android.Paths
+}
+
+var _ genrule.SourceFileGenerator = (*mojomSrcjar)(nil)
+
+func (m *mojomSrcjar) DepsMutator(ctx android.BottomUpMutatorContext) {
+	m.properties.extractSources(ctx)
+}
+
+func (m *mojomSrcjar) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	srcjars := m.properties.generateBuildActions(
+		ctx,
+		"java",
+		[]mojomSrcsRuleDescription{
+			{
+				generatedExtensions: []string{".mojom.srcjar"},
+				extraFlags:          "",
+			},
+		},
+	)
+
+	out := android.PathForModuleGen(ctx, m.properties.Srcjar)
+	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
+		Rule:   mergeSrcjarsRule,
+		Inputs: srcjars,
+		Output: out,
+	})
+	m.generatedSrcs = append(m.generatedSrcs, out)
+}
+
+func (m *mojomSrcjar) GeneratedHeaderDirs() android.Paths {
+	return nil
+}
+
+func (m *mojomSrcjar) GeneratedDeps() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func (m *mojomSrcjar) GeneratedSourceFiles() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func (m *mojomSrcjar) Srcs() android.Paths {
+	return append(android.Paths{}, m.generatedSrcs...)
+}
+
+func mojomSrcjarFactory() android.Module {
+	m := &mojomSrcjar{}
+	m.AddProperties(&m.properties)
+	android.InitAndroidModule(m)
+	return m
+}