diff --git a/cc/snapshot_utils.go b/cc/snapshot_utils.go
index a3d52e6..e841a54 100644
--- a/cc/snapshot_utils.go
+++ b/cc/snapshot_utils.go
@@ -13,6 +13,8 @@
 // limitations under the License.
 package cc
 
+// This file contains utility types and functions for VNDK / vendor snapshot.
+
 import (
 	"android/soong/android"
 )
@@ -21,15 +23,24 @@
 	headerExts = []string{".h", ".hh", ".hpp", ".hxx", ".h++", ".inl", ".inc", ".ipp", ".h.generic"}
 )
 
+// snapshotLibraryInterface is an interface for libraries captured to VNDK / vendor snapshots.
 type snapshotLibraryInterface interface {
 	libraryInterface
+
+	// collectHeadersForSnapshot is called in GenerateAndroidBuildActions for snapshot aware
+	// modules (See isSnapshotAware below).
+	// This function should gather all headers needed for snapshot.
 	collectHeadersForSnapshot(ctx android.ModuleContext)
+
+	// snapshotHeaders should return collected headers by collectHeadersForSnapshot.
+	// Calling snapshotHeaders before collectHeadersForSnapshot is an error.
 	snapshotHeaders() android.Paths
 }
 
 var _ snapshotLibraryInterface = (*prebuiltLibraryLinker)(nil)
 var _ snapshotLibraryInterface = (*libraryDecorator)(nil)
 
+// snapshotMap is a helper wrapper to a map from base module name to snapshot module name.
 type snapshotMap struct {
 	snapshots map[string]string
 }
@@ -57,43 +68,14 @@
 	return snapshot, found
 }
 
-func isSnapshotAware(ctx android.ModuleContext, m *Module, apexInfo android.ApexInfo) bool {
-	if _, _, ok := isVndkSnapshotLibrary(ctx.DeviceConfig(), m, apexInfo); ok {
+// shouldCollectHeadersForSnapshot determines if the module is a possible candidate for snapshot.
+// If it's true, collectHeadersForSnapshot will be called in GenerateAndroidBuildActions.
+func shouldCollectHeadersForSnapshot(ctx android.ModuleContext, m *Module, apexInfo android.ApexInfo) bool {
+	if _, _, ok := isVndkSnapshotAware(ctx.DeviceConfig(), m, apexInfo); ok {
 		return ctx.Config().VndkSnapshotBuildArtifacts()
-	} else if isVendorSnapshotModule(m, isVendorProprietaryPath(ctx.ModuleDir()), apexInfo) ||
-		isRecoverySnapshotModule(m, isVendorProprietaryPath(ctx.ModuleDir()), apexInfo) {
+	} else if isVendorSnapshotAware(m, isVendorProprietaryPath(ctx.ModuleDir()), apexInfo) ||
+		isRecoverySnapshotAware(m, isRecoveryProprietaryPath(ctx.ModuleDir()), apexInfo) {
 		return true
 	}
 	return false
 }
-
-func copyFile(ctx android.SingletonContext, path android.Path, out string) android.OutputPath {
-	outPath := android.PathForOutput(ctx, out)
-	ctx.Build(pctx, android.BuildParams{
-		Rule:        android.Cp,
-		Input:       path,
-		Output:      outPath,
-		Description: "Cp " + out,
-		Args: map[string]string{
-			"cpFlags": "-f -L",
-		},
-	})
-	return outPath
-}
-
-func combineNotices(ctx android.SingletonContext, paths android.Paths, out string) android.OutputPath {
-	outPath := android.PathForOutput(ctx, out)
-	ctx.Build(pctx, android.BuildParams{
-		Rule:        android.Cat,
-		Inputs:      paths,
-		Output:      outPath,
-		Description: "combine notices for " + out,
-	})
-	return outPath
-}
-
-func writeStringToFile(ctx android.SingletonContext, content, out string) android.OutputPath {
-	outPath := android.PathForOutput(ctx, out)
-	android.WriteFileRule(ctx, outPath, content)
-	return outPath
-}