Add support for protoc plugins

Add a proto.plugin property to allow specifying a custom protoc
plugin to generate the code.

Fixes: 70706119
Test: m am StreamingProtoTest
Change-Id: I1ecdd346284b42bbcc8297019d98d2cd564eb94c
diff --git a/cc/proto.go b/cc/proto.go
index 5a96ae7..f818edc 100644
--- a/cc/proto.go
+++ b/cc/proto.go
@@ -39,7 +39,7 @@
 		headerFile = android.PathForModuleGen(ctx, "proto", pathtools.ReplaceExtension(rel, "pb.h"))
 	}
 
-	protoDeps := flags.protoDeps
+	protoDeps := flags.proto.Deps
 	if flags.protoOptionsFile {
 		optionsFile := pathtools.ReplaceExtension(protoFile.String(), "options")
 		optionsPath := android.PathForSource(ctx, optionsFile)
@@ -59,53 +59,55 @@
 	return ccFile, headerFile
 }
 
-func protoDeps(ctx BaseModuleContext, deps Deps, p *android.ProtoProperties, static bool) Deps {
+func protoDeps(ctx DepsContext, deps Deps, p *android.ProtoProperties, static bool) Deps {
 	var lib string
 
-	switch String(p.Proto.Type) {
-	case "full":
-		if ctx.useSdk() {
-			lib = "libprotobuf-cpp-full-ndk"
+	if String(p.Proto.Plugin) == "" {
+		switch String(p.Proto.Type) {
+		case "full":
+			if ctx.useSdk() {
+				lib = "libprotobuf-cpp-full-ndk"
+				static = true
+			} else {
+				lib = "libprotobuf-cpp-full"
+			}
+		case "lite", "":
+			if ctx.useSdk() {
+				lib = "libprotobuf-cpp-lite-ndk"
+				static = true
+			} else {
+				lib = "libprotobuf-cpp-lite"
+			}
+		case "nanopb-c":
+			lib = "libprotobuf-c-nano"
 			static = true
-		} else {
-			lib = "libprotobuf-cpp-full"
-		}
-	case "lite", "":
-		if ctx.useSdk() {
-			lib = "libprotobuf-cpp-lite-ndk"
+		case "nanopb-c-enable_malloc":
+			lib = "libprotobuf-c-nano-enable_malloc"
 			static = true
-		} else {
-			lib = "libprotobuf-cpp-lite"
+		case "nanopb-c-16bit":
+			lib = "libprotobuf-c-nano-16bit"
+			static = true
+		case "nanopb-c-enable_malloc-16bit":
+			lib = "libprotobuf-c-nano-enable_malloc-16bit"
+			static = true
+		case "nanopb-c-32bit":
+			lib = "libprotobuf-c-nano-32bit"
+			static = true
+		case "nanopb-c-enable_malloc-32bit":
+			lib = "libprotobuf-c-nano-enable_malloc-32bit"
+			static = true
+		default:
+			ctx.PropertyErrorf("proto.type", "unknown proto type %q",
+				String(p.Proto.Type))
 		}
-	case "nanopb-c":
-		lib = "libprotobuf-c-nano"
-		static = true
-	case "nanopb-c-enable_malloc":
-		lib = "libprotobuf-c-nano-enable_malloc"
-		static = true
-	case "nanopb-c-16bit":
-		lib = "libprotobuf-c-nano-16bit"
-		static = true
-	case "nanopb-c-enable_malloc-16bit":
-		lib = "libprotobuf-c-nano-enable_malloc-16bit"
-		static = true
-	case "nanopb-c-32bit":
-		lib = "libprotobuf-c-nano-32bit"
-		static = true
-	case "nanopb-c-enable_malloc-32bit":
-		lib = "libprotobuf-c-nano-enable_malloc-32bit"
-		static = true
-	default:
-		ctx.PropertyErrorf("proto.type", "unknown proto type %q",
-			String(p.Proto.Type))
-	}
 
-	if static {
-		deps.StaticLibs = append(deps.StaticLibs, lib)
-		deps.ReexportStaticLibHeaders = append(deps.ReexportStaticLibHeaders, lib)
-	} else {
-		deps.SharedLibs = append(deps.SharedLibs, lib)
-		deps.ReexportSharedLibHeaders = append(deps.ReexportSharedLibHeaders, lib)
+		if static {
+			deps.StaticLibs = append(deps.StaticLibs, lib)
+			deps.ReexportStaticLibHeaders = append(deps.ReexportStaticLibHeaders, lib)
+		} else {
+			deps.SharedLibs = append(deps.SharedLibs, lib)
+			deps.ReexportSharedLibHeaders = append(deps.ReexportSharedLibHeaders, lib)
+		}
 	}
 
 	return deps
@@ -120,33 +122,35 @@
 	}
 	flags.GlobalFlags = append(flags.GlobalFlags, "-I"+flags.proto.Dir.String())
 
-	var plugin string
+	if String(p.Proto.Plugin) == "" {
+		var plugin string
 
-	switch String(p.Proto.Type) {
-	case "nanopb-c", "nanopb-c-enable_malloc", "nanopb-c-16bit", "nanopb-c-enable_malloc-16bit", "nanopb-c-32bit", "nanopb-c-enable_malloc-32bit":
-		flags.protoC = true
-		flags.protoOptionsFile = true
-		flags.proto.OutTypeFlag = "--nanopb_out"
-		plugin = "protoc-gen-nanopb"
-	case "full":
-		flags.proto.OutTypeFlag = "--cpp_out"
-	case "lite":
-		flags.proto.OutTypeFlag = "--cpp_out"
-		flags.proto.OutParams = append(flags.proto.OutParams, "lite")
-	case "":
-		// TODO(b/119714316): this should be equivalent to "lite" in
-		// order to match protoDeps, but some modules are depending on
-		// this behavior
-		flags.proto.OutTypeFlag = "--cpp_out"
-	default:
-		ctx.PropertyErrorf("proto.type", "unknown proto type %q",
-			String(p.Proto.Type))
-	}
+		switch String(p.Proto.Type) {
+		case "nanopb-c", "nanopb-c-enable_malloc", "nanopb-c-16bit", "nanopb-c-enable_malloc-16bit", "nanopb-c-32bit", "nanopb-c-enable_malloc-32bit":
+			flags.protoC = true
+			flags.protoOptionsFile = true
+			flags.proto.OutTypeFlag = "--nanopb_out"
+			plugin = "protoc-gen-nanopb"
+		case "full":
+			flags.proto.OutTypeFlag = "--cpp_out"
+		case "lite":
+			flags.proto.OutTypeFlag = "--cpp_out"
+			flags.proto.OutParams = append(flags.proto.OutParams, "lite")
+		case "":
+			// TODO(b/119714316): this should be equivalent to "lite" in
+			// order to match protoDeps, but some modules are depending on
+			// this behavior
+			flags.proto.OutTypeFlag = "--cpp_out"
+		default:
+			ctx.PropertyErrorf("proto.type", "unknown proto type %q",
+				String(p.Proto.Type))
+		}
 
-	if plugin != "" {
-		path := ctx.Config().HostToolPath(ctx, plugin)
-		flags.protoDeps = append(flags.protoDeps, path)
-		flags.proto.Flags = append(flags.proto.Flags, "--plugin="+path.String())
+		if plugin != "" {
+			path := ctx.Config().HostToolPath(ctx, plugin)
+			flags.proto.Deps = append(flags.proto.Deps, path)
+			flags.proto.Flags = append(flags.proto.Flags, "--plugin="+path.String())
+		}
 	}
 
 	return flags