Save compilation units in protobuf format.

Bug: 146224091
Test: manual
Change-Id: I7a856bab13f54c78efa0061421c3fcb9341bc6e7
diff --git a/android/config.go b/android/config.go
index 3c49c1a..1cb543d 100644
--- a/android/config.go
+++ b/android/config.go
@@ -835,6 +835,14 @@
 	return c.Getenv("XREF_CORPUS")
 }
 
+// Returns Compilation Unit encoding to use. Can be 'json' (default), 'proto' or 'all'.
+func (c *config) XrefCuEncoding() string {
+	if enc := c.Getenv("KYTHE_KZIP_ENCODING"); enc != "" {
+		return enc
+	}
+	return "json"
+}
+
 func (c *config) EmitXrefRules() bool {
 	return c.XrefCorpusName() != ""
 }
diff --git a/build_kzip.bash b/build_kzip.bash
index 02b346d..89cd067 100755
--- a/build_kzip.bash
+++ b/build_kzip.bash
@@ -6,12 +6,14 @@
 # The following environment variables affect the result:
 #   BUILD_NUMBER          build number, used to generate unique ID (will use UUID if not set)
 #   DIST_DIR              where the resulting all.kzip will be placed
+#   KYTHE_KZIP_ENCODING   proto or json (proto is default)
 #   OUT_DIR               output directory (out if not specified})
 #   TARGET_BUILD_VARIANT  variant, e.g., `userdebug`
 #   TARGET_PRODUCT        target device name, e.g., 'aosp_blueline'
 #   XREF_CORPUS           source code repository URI, e.g., 'android.googlesource.com/platform/superproject'
 
 : ${BUILD_NUMBER:=$(uuidgen)}
+: ${KYTHE_KZIP_ENCODING:=proto}
 
 # The extraction might fail for some source files, so run with -k and then check that
 # sufficiently many files were generated.
diff --git a/cc/builder.go b/cc/builder.go
index 1ec323f..5f0da5f 100644
--- a/cc/builder.go
+++ b/cc/builder.go
@@ -238,9 +238,13 @@
 	_ = pctx.SourcePathVariable("kytheVnames", "build/soong/vnames.json")
 	_ = pctx.VariableFunc("kytheCorpus",
 		func(ctx android.PackageVarContext) string { return ctx.Config().XrefCorpusName() })
+	_ = pctx.VariableFunc("kytheCuEncoding",
+		func(ctx android.PackageVarContext) string { return ctx.Config().XrefCuEncoding() })
 	kytheExtract = pctx.StaticRule("kythe",
 		blueprint.RuleParams{
-			Command:     "rm -f $out && KYTHE_CORPUS=${kytheCorpus} KYTHE_OUTPUT_FILE=$out KYTHE_VNAMES=$kytheVnames $cxxExtractor $cFlags $in ",
+			Command: `rm -f $out && ` +
+				`KYTHE_CORPUS=${kytheCorpus} KYTHE_OUTPUT_FILE=$out KYTHE_VNAMES=$kytheVnames KYTHE_KZIP_ENCODING=${kytheCuEncoding} ` +
+				`$cxxExtractor $cFlags $in `,
 			CommandDeps: []string{"$cxxExtractor", "$kytheVnames"},
 		},
 		"cFlags")
diff --git a/java/builder.go b/java/builder.go
index 417a7fa..26a49ea 100644
--- a/java/builder.go
+++ b/java/builder.go
@@ -64,6 +64,8 @@
 
 	_ = pctx.VariableFunc("kytheCorpus",
 		func(ctx android.PackageVarContext) string { return ctx.Config().XrefCorpusName() })
+	_ = pctx.VariableFunc("kytheCuEncoding",
+		func(ctx android.PackageVarContext) string { return ctx.Config().XrefCuEncoding() })
 	_ = pctx.SourcePathVariable("kytheVnames", "build/soong/vnames.json")
 	// Run it with -add-opens=java.base/java.nio=ALL-UNNAMED to avoid JDK9's warning about
 	// "Illegal reflective access by com.google.protobuf.Utf8$UnsafeProcessor ...
@@ -76,6 +78,7 @@
 				`KYTHE_ROOT_DIRECTORY=. KYTHE_OUTPUT_FILE=$out ` +
 				`KYTHE_CORPUS=${kytheCorpus} ` +
 				`KYTHE_VNAMES=${kytheVnames} ` +
+				`KYTHE_KZIP_ENCODING=${kytheCuEncoding} ` +
 				`${config.SoongJavacWrapper} ${config.JavaCmd} ` +
 				`--add-opens=java.base/java.nio=ALL-UNNAMED ` +
 				`-jar ${config.JavaKytheExtractorJar} ` +