Search for PGO profiles in PGO_ADDITIONAL_PROFILE_DIRS

This variable can be set in BoardConfig.mk to specify a list of
additional paths that contain PGO profiles.  These directories are
searched after the predefined paths in soong/cc/pgo.go while finding
PGO profiles.

Test: Set this variable in a BoardConfig and verify that such profiles
are found and that these paths are searched after the predefined paths
in soong/cc/pgo.go.

Change-Id: I0bb9523de614d0f23aba8d51c887d8fc8f41c993
diff --git a/android/config.go b/android/config.go
index b5ec975..1e5dd52 100644
--- a/android/config.go
+++ b/android/config.go
@@ -710,6 +710,10 @@
 	return coverage
 }
 
+func (c *deviceConfig) PgoAdditionalProfileDirs() []string {
+	return c.config.ProductVariables.PgoAdditionalProfileDirs
+}
+
 func (c *config) IntegerOverflowDisabledForPath(path string) bool {
 	if c.ProductVariables.IntegerOverflowExcludePaths == nil {
 		return false
diff --git a/android/variable.go b/android/variable.go
index 2c2a0cf..328074a 100644
--- a/android/variable.go
+++ b/android/variable.go
@@ -205,6 +205,8 @@
 	ExtraVndkVersions []string `json:",omitempty"`
 
 	NamespacesToExport []string `json:",omitempty"`
+
+	PgoAdditionalProfileDirs []string `json:",omitempty"`
 }
 
 func boolPtr(v bool) *bool {
diff --git a/cc/pgo.go b/cc/pgo.go
index 3ce67be..1e70339 100644
--- a/cc/pgo.go
+++ b/cc/pgo.go
@@ -27,17 +27,24 @@
 	// some functions
 	profileUseOtherFlags = []string{"-Wno-backend-plugin"}
 
-	pgoProfileProjects = []string{
+	globalPgoProfileProjects = []string{
 		"toolchain/pgo-profiles",
 		"vendor/google_data/pgo-profiles",
 	}
 )
 
+const pgoProfileProjectsConfigKey = "PgoProfileProjects"
 const profileInstrumentFlag = "-fprofile-generate=/data/local/tmp"
 const profileSamplingFlag = "-gline-tables-only"
 const profileUseInstrumentFormat = "-fprofile-use=%s"
 const profileUseSamplingFormat = "-fprofile-sample-use=%s"
 
+func getPgoProfileProjects(config android.DeviceConfig) []string {
+	return config.OnceStringSlice(pgoProfileProjectsConfigKey, func() []string {
+		return append(globalPgoProfileProjects, config.PgoAdditionalProfileDirs()...)
+	})
+}
+
 func recordMissingProfileFile(ctx ModuleContext, missing string) {
 	getNamedMapForConfig(ctx.Config(), modulesMissingProfileFile).Store(missing, true)
 }
@@ -92,8 +99,8 @@
 }
 
 func (props *PgoProperties) getPgoProfileFile(ctx ModuleContext) android.OptionalPath {
-	// Test if the profile_file is present in any of the pgoProfileProjects
-	for _, profileProject := range pgoProfileProjects {
+	// Test if the profile_file is present in any of the PGO profile projects
+	for _, profileProject := range getPgoProfileProjects(ctx.DeviceConfig()) {
 		path := android.ExistentPathForSource(ctx, "", profileProject, *props.Pgo.Profile_file)
 		if path.Valid() {
 			return path