Create a new product variable to gate blueprint files

Users can use this feature by
1. Setting PRODUCT_INCLUDE_TAGS += <val> in their product mk files
2. Set
```
blueprint_packge_includes {
  match_al: ["<val>"],
}

other_module_type {name: foo}
other_module_type {name: bar}
```

bar and foo will be included if and only if <val> is set

Test: Unit tests in blueprint
Test: TH

Change-Id: I32eed4e3b5ac47fb565c62d13d8881fa984c86f4

android/config.go

@@ -1111,6 +1111,10 @@ func (c *config) ExportedNamespaces() []string {
 	return append([]string(nil), c.productVariables.NamespacesToExport...)
 }
 
+func (c *config) IncludeTags() []string {
+	return c.productVariables.IncludeTags
+}
+
 func (c *config) HostStaticBinaries() bool {
 	return Bool(c.productVariables.HostStaticBinaries)
 }

android/register.go

@@ -161,6 +161,7 @@ type Context struct {
 func NewContext(config Config) *Context {
 	ctx := &Context{blueprint.NewContext(), config}
 	ctx.SetSrcDir(absSrcDir)
+	ctx.AddIncludeTags(config.IncludeTags()...)
 	return ctx
 }
 

android/variable.go

@@ -452,6 +452,8 @@ type productVariables struct {
 	GenerateAidlNdkPlatformBackend bool `json:",omitempty"`
 
 	IgnorePrefer32OnDevice bool `json:",omitempty"`
+
+	IncludeTags []string `json:",omitempty"`
 }
 
 func boolPtr(v bool) *bool {

cmd/soong_build/main.go

@@ -114,6 +114,7 @@ func newContext(configuration android.Config) *android.Context {
 	ctx := android.NewContext(configuration)
 	ctx.SetNameInterface(newNameResolver(configuration))
 	ctx.SetAllowMissingDependencies(configuration.AllowMissingDependencies())
+	ctx.AddIncludeTags(configuration.IncludeTags()...)
 	return ctx
 }
 

ui/build/config.go

@@ -111,6 +111,8 @@ type configImpl struct {
 	metricsUploader string
 
 	bazelForceEnabledModules string
+
+	includeTags []string
 }
 
 const srcDirFileCheck = "build/soong/root.bp"
@@ -1079,6 +1081,14 @@ func (c *configImpl) Parallel() int {
 	return c.parallel
 }
 
+func (c *configImpl) GetIncludeTags() []string {
+	return c.includeTags
+}
+
+func (c *configImpl) SetIncludeTags(i []string) {
+	c.includeTags = i
+}
+
 func (c *configImpl) HighmemParallel() int {
 	if i, ok := c.environ.GetInt("NINJA_HIGHMEM_NUM_JOBS"); ok {
 		return i

ui/build/dumpvars.go

@@ -139,6 +139,7 @@ func dumpMakeVars(ctx Context, config Config, goals, vars []string, write_soong_
 var BannerVars = []string{
 	"PLATFORM_VERSION_CODENAME",
 	"PLATFORM_VERSION",
+	"PRODUCT_INCLUDE_TAGS",
 	"TARGET_PRODUCT",
 	"TARGET_BUILD_VARIANT",
 	"TARGET_BUILD_APPS",
@@ -289,4 +290,5 @@ func runMakeProductConfig(ctx Context, config Config) {
 	config.SetBuildBrokenDupRules(makeVars["BUILD_BROKEN_DUP_RULES"] == "true")
 	config.SetBuildBrokenUsesNetwork(makeVars["BUILD_BROKEN_USES_NETWORK"] == "true")
 	config.SetBuildBrokenNinjaUsesEnvVars(strings.Fields(makeVars["BUILD_BROKEN_NINJA_USES_ENV_VARS"]))
+	config.SetIncludeTags(strings.Fields(makeVars["PRODUCT_INCLUDE_TAGS"]))
 }

ui/build/soong.go

@@ -403,6 +403,7 @@ func bootstrapBlueprint(ctx Context, config Config) {
 	}
 
 	blueprintCtx := blueprint.NewContext()
+	blueprintCtx.AddIncludeTags(config.GetIncludeTags()...)
 	blueprintCtx.SetIgnoreUnknownModuleTypes(true)
 	blueprintConfig := BlueprintConfig{
 		soongOutDir: config.SoongOutDir(),